diff --git a/CHANGELOG.md b/CHANGELOG.md
index c8c3f95425..356789350f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@
 * [FEATURE] Store Gateway: Add an in-memory chunk cache. #6245
 * [FEATURE] Chunk Cache: Support multi level cache and add metrics. #6249
 * [FEATURE] Distributor: Accept multiple HA Tracker pairs in the same request. #6256
+* [ENHANCEMENT] Query Frontend/Querier: Add an experimental flag `-querier.enable-promql-experimental-functions` to enable experimental promQL functions. #6355
 * [ENHANCEMENT] OTLP: Add `-distributor.otlp-max-recv-msg-size` flag to limit OTLP request size in bytes. #6333
 * [ENHANCEMENT] S3 Bucket Client: Add a list objects version configs to configure list api object version. #6280
 * [ENHANCEMENT] OpenStack Swift: Add application credential configs for Openstack swift object storage backend. #6255
diff --git a/docs/blocks-storage/querier.md b/docs/blocks-storage/querier.md
index 4fc1958ee0..9c78746070 100644
--- a/docs/blocks-storage/querier.md
+++ b/docs/blocks-storage/querier.md
@@ -253,6 +253,10 @@ querier:
   # evaluation like at Query Frontend or Ruler.
   # CLI flag: -querier.ignore-max-query-length
   [ignore_max_query_length: <boolean> | default = false]
+
+  # [Experimental] If true, experimental promQL functions are enabled.
+  # CLI flag: -querier.enable-promql-experimental-functions
+  [enable_promql_experimental_functions: <boolean> | default = false]
 ```
 
 ### `blocks_storage_config`
diff --git a/docs/configuration/config-file-reference.md b/docs/configuration/config-file-reference.md
index deb79957b7..67ae897e02 100644
--- a/docs/configuration/config-file-reference.md
+++ b/docs/configuration/config-file-reference.md
@@ -3997,6 +3997,10 @@ store_gateway_client:
 # like at Query Frontend or Ruler.
 # CLI flag: -querier.ignore-max-query-length
 [ignore_max_query_length: <boolean> | default = false]
+
+# [Experimental] If true, experimental promQL functions are enabled.
+# CLI flag: -querier.enable-promql-experimental-functions
+[enable_promql_experimental_functions: <boolean> | default = false]
 ```
 
 ### `query_frontend_config`
diff --git a/integration/query_fuzz_test.go b/integration/query_fuzz_test.go
index fb97189250..3f7e47c3ae 100644
--- a/integration/query_fuzz_test.go
+++ b/integration/query_fuzz_test.go
@@ -52,6 +52,123 @@ func init() {
 	}
 }
 
+func TestExperimentalPromQLFuncsWithPrometheus(t *testing.T) {
+	prometheusLatestImage := "quay.io/prometheus/prometheus:v2.55.1"
+	s, err := e2e.NewScenario(networkName)
+	require.NoError(t, err)
+	defer s.Close()
+
+	// Start dependencies.
+	consul := e2edb.NewConsulWithName("consul")
+	require.NoError(t, s.StartAndWaitReady(consul))
+
+	baseFlags := mergeFlags(AlertmanagerLocalFlags(), BlocksStorageFlags())
+	flags := mergeFlags(
+		baseFlags,
+		map[string]string{
+			"-blocks-storage.tsdb.head-compaction-interval":    "4m",
+			"-blocks-storage.tsdb.block-ranges-period":         "2h",
+			"-blocks-storage.tsdb.ship-interval":               "1h",
+			"-blocks-storage.bucket-store.sync-interval":       "1s",
+			"-blocks-storage.tsdb.retention-period":            "24h",
+			"-blocks-storage.bucket-store.index-cache.backend": tsdb.IndexCacheBackendInMemory,
+			"-querier.query-store-for-labels-enabled":          "true",
+			// Ingester.
+			"-ring.store":      "consul",
+			"-consul.hostname": consul.NetworkHTTPEndpoint(),
+			// Distributor.
+			"-distributor.replication-factor": "1",
+			// Store-gateway.
+			"-store-gateway.sharding-enabled": "false",
+			// alert manager
+			"-alertmanager.web.external-url":      "http://localhost/alertmanager",
+			"-frontend.query-vertical-shard-size": "1",
+			"-frontend.max-cache-freshness":       "1m",
+			// enable experimental promQL funcs
+			"-querier.enable-promql-experimental-functions": "true",
+		},
+	)
+	// make alert manager config dir
+	require.NoError(t, writeFileToSharedDir(s, "alertmanager_configs", []byte{}))
+
+	minio := e2edb.NewMinio(9000, flags["-blocks-storage.s3.bucket-name"])
+	require.NoError(t, s.StartAndWaitReady(minio))
+
+	cortex := e2ecortex.NewSingleBinary("cortex", flags, "")
+	require.NoError(t, s.StartAndWaitReady(cortex))
+
+	// Wait until Cortex replicas have updated the ring state.
+	require.NoError(t, cortex.WaitSumMetrics(e2e.Equals(float64(512)), "cortex_ring_tokens_total"))
+
+	now := time.Now()
+	start := now.Add(-time.Hour * 2)
+	end := now.Add(-time.Hour)
+	numSeries := 10
+	numSamples := 60
+	lbls := make([]labels.Labels, 0, numSeries*2)
+	scrapeInterval := time.Minute
+	statusCodes := []string{"200", "400", "404", "500", "502"}
+	for i := 0; i < numSeries; i++ {
+		lbls = append(lbls, labels.Labels{
+			{Name: labels.MetricName, Value: "test_series_a"},
+			{Name: "job", Value: "test"},
+			{Name: "series", Value: strconv.Itoa(i % 3)},
+			{Name: "status_code", Value: statusCodes[i%5]},
+		})
+
+		lbls = append(lbls, labels.Labels{
+			{Name: labels.MetricName, Value: "test_series_b"},
+			{Name: "job", Value: "test"},
+			{Name: "series", Value: strconv.Itoa((i + 1) % 3)},
+			{Name: "status_code", Value: statusCodes[(i+1)%5]},
+		})
+	}
+
+	ctx := context.Background()
+	rnd := rand.New(rand.NewSource(time.Now().Unix()))
+
+	dir := filepath.Join(s.SharedDir(), "data")
+	err = os.MkdirAll(dir, os.ModePerm)
+	require.NoError(t, err)
+	storage, err := e2ecortex.NewS3ClientForMinio(minio, flags["-blocks-storage.s3.bucket-name"])
+	require.NoError(t, err)
+	bkt := bucket.NewUserBucketClient("user-1", storage.GetBucket(), nil)
+	id, err := e2e.CreateBlock(ctx, rnd, dir, lbls, numSamples, start.UnixMilli(), end.UnixMilli(), scrapeInterval.Milliseconds(), 10)
+	require.NoError(t, err)
+	err = block.Upload(ctx, log.Logger, bkt, filepath.Join(dir, id.String()), metadata.NoneFunc)
+	require.NoError(t, err)
+
+	// Wait for querier and store to sync blocks.
+	require.NoError(t, cortex.WaitSumMetricsWithOptions(e2e.Equals(float64(1)), []string{"cortex_blocks_meta_synced"}, e2e.WaitMissingMetrics, e2e.WithLabelMatchers(labels.MustNewMatcher(labels.MatchEqual, "component", "store-gateway"))))
+	require.NoError(t, cortex.WaitSumMetricsWithOptions(e2e.Equals(float64(1)), []string{"cortex_blocks_meta_synced"}, e2e.WaitMissingMetrics, e2e.WithLabelMatchers(labels.MustNewMatcher(labels.MatchEqual, "component", "querier"))))
+	require.NoError(t, cortex.WaitSumMetricsWithOptions(e2e.Equals(float64(1)), []string{"cortex_bucket_store_blocks_loaded"}, e2e.WaitMissingMetrics))
+
+	c1, err := e2ecortex.NewClient("", cortex.HTTPEndpoint(), "", "", "user-1")
+	require.NoError(t, err)
+
+	err = writeFileToSharedDir(s, "prometheus.yml", []byte(""))
+	require.NoError(t, err)
+	prom := e2edb.NewPrometheus(prometheusLatestImage, map[string]string{
+		"--enable-feature": "promql-experimental-functions",
+	})
+	require.NoError(t, s.StartAndWaitReady(prom))
+
+	c2, err := e2ecortex.NewPromQueryClient(prom.HTTPEndpoint())
+	require.NoError(t, err)
+
+	waitUntilReady(t, ctx, c1, c2, `{job="test"}`, start, end)
+
+	opts := []promqlsmith.Option{
+		promqlsmith.WithEnableOffset(true),
+		promqlsmith.WithEnableAtModifier(true),
+		promqlsmith.WithEnabledFunctions(enabledFunctions),
+		promqlsmith.WithEnableExperimentalPromQLFunctions(true),
+	}
+	ps := promqlsmith.New(rnd, lbls, opts...)
+
+	runQueryFuzzTestCases(t, ps, c1, c2, end, start, end, scrapeInterval, 1000)
+}
+
 func TestDisableChunkTrimmingFuzz(t *testing.T) {
 	s, err := e2e.NewScenario(networkName)
 	require.NoError(t, err)
@@ -1410,6 +1527,15 @@ func runQueryFuzzTestCases(t *testing.T, ps *promqlsmith.PromQLSmith, c1, c2 *e2
 func isValidQuery(generatedQuery parser.Expr, maxDepth int) bool {
 	isValid := true
 	currentDepth := 0
+	// TODO(SungJin1212): Test limitk, limit_ratio
+	if strings.Contains(generatedQuery.String(), "limitk") {
+		// current skip the limitk
+		return false
+	}
+	if strings.Contains(generatedQuery.String(), "limit_ratio") {
+		// current skip the limit_ratio
+		return false
+	}
 	parser.Inspect(generatedQuery, func(node parser.Node, path []parser.Node) error {
 		if currentDepth > maxDepth {
 			isValid = false
diff --git a/pkg/cortex/modules.go b/pkg/cortex/modules.go
index 00f0b10a20..222d321168 100644
--- a/pkg/cortex/modules.go
+++ b/pkg/cortex/modules.go
@@ -508,6 +508,7 @@ func (t *Cortex) initQueryFrontendTripperware() (serv services.Service, err erro
 		t.Cfg.Querier.DefaultEvaluationInterval,
 		t.Cfg.Querier.MaxSubQuerySteps,
 		t.Cfg.Querier.LookbackDelta,
+		t.Cfg.Querier.EnablePromQLExperimentalFunctions,
 	)
 
 	return services.NewIdleService(nil, func(_ error) error {
diff --git a/pkg/querier/querier.go b/pkg/querier/querier.go
index 34d1f8b19e..784aef3bee 100644
--- a/pkg/querier/querier.go
+++ b/pkg/querier/querier.go
@@ -16,6 +16,7 @@ import (
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/promql"
+	"github.com/prometheus/prometheus/promql/parser"
 	"github.com/prometheus/prometheus/storage"
 	"github.com/prometheus/prometheus/tsdb/chunkenc"
 	"github.com/prometheus/prometheus/util/annotations"
@@ -89,7 +90,8 @@ type Config struct {
 	ThanosEngine bool `yaml:"thanos_engine"`
 
 	// Ignore max query length check at Querier.
-	IgnoreMaxQueryLength bool `yaml:"ignore_max_query_length"`
+	IgnoreMaxQueryLength              bool `yaml:"ignore_max_query_length"`
+	EnablePromQLExperimentalFunctions bool `yaml:"enable_promql_experimental_functions"`
 }
 
 var (
@@ -132,6 +134,7 @@ func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
 	f.BoolVar(&cfg.ThanosEngine, "querier.thanos-engine", false, "Experimental. Use Thanos promql engine https://github.com/thanos-io/promql-engine rather than the Prometheus promql engine.")
 	f.Int64Var(&cfg.MaxSubQuerySteps, "querier.max-subquery-steps", 0, "Max number of steps allowed for every subquery expression in query. Number of steps is calculated using subquery range / step. A value > 0 enables it.")
 	f.BoolVar(&cfg.IgnoreMaxQueryLength, "querier.ignore-max-query-length", false, "If enabled, ignore max query length check at Querier select method. Users can choose to ignore it since the validation can be done before Querier evaluation like at Query Frontend or Ruler.")
+	f.BoolVar(&cfg.EnablePromQLExperimentalFunctions, "querier.enable-promql-experimental-functions", false, "[Experimental] If true, experimental promQL functions are enabled.")
 }
 
 // Validate the config
@@ -204,6 +207,9 @@ func New(cfg Config, limits *validation.Overrides, distributor Distributor, stor
 	})
 	maxConcurrentMetric.Set(float64(cfg.MaxConcurrent))
 
+	// set EnableExperimentalFunctions
+	parser.EnableExperimentalFunctions = cfg.EnablePromQLExperimentalFunctions
+
 	var queryEngine promql.QueryEngine
 	opts := promql.EngineOpts{
 		Logger:               logger,
diff --git a/pkg/querier/tripperware/merge.go b/pkg/querier/tripperware/merge.go
index e1d376ac6d..a85725c541 100644
--- a/pkg/querier/tripperware/merge.go
+++ b/pkg/querier/tripperware/merge.go
@@ -288,9 +288,9 @@ func sortPlanForQuery(q string) (sortPlan, error) {
 	if err != nil {
 		return 0, err
 	}
-	// Check if the root expression is topk or bottomk
+	// Check if the root expression is topk, bottomk, limitk, or limit_ratio
 	if aggr, ok := expr.(*promqlparser.AggregateExpr); ok {
-		if aggr.Op == promqlparser.TOPK || aggr.Op == promqlparser.BOTTOMK {
+		if aggr.Op == promqlparser.TOPK || aggr.Op == promqlparser.BOTTOMK || aggr.Op == promqlparser.LIMITK || aggr.Op == promqlparser.LIMIT_RATIO {
 			return mergeOnly, nil
 		}
 	}
@@ -303,6 +303,12 @@ func sortPlanForQuery(q string) (sortPlan, error) {
 				if n.Func.Name == "sort_desc" {
 					sortDesc = true
 				}
+				if n.Func.Name == "sort_by_label" {
+					sortAsc = true
+				}
+				if n.Func.Name == "sort_by_label_desc" {
+					sortDesc = true
+				}
 			}
 		}
 		return sortAsc, sortDesc
diff --git a/pkg/querier/tripperware/merge_test.go b/pkg/querier/tripperware/merge_test.go
index 6a51ca7072..7ee5b0cbbd 100644
--- a/pkg/querier/tripperware/merge_test.go
+++ b/pkg/querier/tripperware/merge_test.go
@@ -4,6 +4,7 @@ import (
 	"testing"
 
 	"github.com/prometheus/prometheus/model/labels"
+	promqlparser "github.com/prometheus/prometheus/promql/parser"
 	"github.com/stretchr/testify/assert"
 
 	"github.com/cortexproject/cortex/pkg/cortexpb"
@@ -618,6 +619,16 @@ func Test_sortPlanForQuery(t *testing.T) {
 			expectedPlan: mergeOnly,
 			err:          false,
 		},
+		{
+			query:        "limitk(10, up)",
+			expectedPlan: mergeOnly,
+			err:          false,
+		},
+		{
+			query:        "limit_ratio(0.1, up)",
+			expectedPlan: mergeOnly,
+			err:          false,
+		},
 		{
 			query:        "1 + topk(10, up)",
 			expectedPlan: sortByLabels,
@@ -633,6 +644,16 @@ func Test_sortPlanForQuery(t *testing.T) {
 			expectedPlan: sortByValuesAsc,
 			err:          false,
 		},
+		{
+			query:        "1 + sort_by_label_desc(sum by (job) (up) )",
+			expectedPlan: sortByValuesDesc,
+			err:          false,
+		},
+		{
+			query:        "sort_by_label(topk by (job) (10, up))",
+			expectedPlan: sortByValuesAsc,
+			err:          false,
+		},
 		{
 			query:        "topk(5, up) by (job) + sort_desc(up)",
 			expectedPlan: sortByValuesDesc,
@@ -652,6 +673,7 @@ func Test_sortPlanForQuery(t *testing.T) {
 
 	for _, tc := range tc {
 		t.Run(tc.query, func(t *testing.T) {
+			promqlparser.EnableExperimentalFunctions = true
 			p, err := sortPlanForQuery(tc.query)
 			if tc.err {
 				assert.Error(t, err)
diff --git a/pkg/querier/tripperware/queryrange/query_range_middlewares_test.go b/pkg/querier/tripperware/queryrange/query_range_middlewares_test.go
index 8ba197865f..5acb18d87e 100644
--- a/pkg/querier/tripperware/queryrange/query_range_middlewares_test.go
+++ b/pkg/querier/tripperware/queryrange/query_range_middlewares_test.go
@@ -80,6 +80,7 @@ func TestRoundTrip(t *testing.T) {
 		time.Minute,
 		0,
 		0,
+		false,
 	)
 
 	for i, tc := range []struct {
diff --git a/pkg/querier/tripperware/roundtrip.go b/pkg/querier/tripperware/roundtrip.go
index 4edcd51cc9..69b46dd66b 100644
--- a/pkg/querier/tripperware/roundtrip.go
+++ b/pkg/querier/tripperware/roundtrip.go
@@ -27,6 +27,7 @@ import (
 	"github.com/opentracing/opentracing-go"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
+	"github.com/prometheus/prometheus/promql/parser"
 	"github.com/thanos-io/thanos/pkg/querysharding"
 	"github.com/weaveworks/common/httpgrpc"
 	"github.com/weaveworks/common/user"
@@ -104,7 +105,12 @@ func NewQueryTripperware(
 	defaultSubQueryInterval time.Duration,
 	maxSubQuerySteps int64,
 	lookbackDelta time.Duration,
+	enablePromQLExperimentalFunctions bool,
 ) Tripperware {
+
+	// set EnableExperimentalFunctions
+	parser.EnableExperimentalFunctions = enablePromQLExperimentalFunctions
+
 	// Per tenant query metrics.
 	queriesPerTenant := promauto.With(registerer).NewCounterVec(prometheus.CounterOpts{
 		Name: "cortex_query_frontend_queries_total",
diff --git a/pkg/querier/tripperware/roundtrip_test.go b/pkg/querier/tripperware/roundtrip_test.go
index 7e6cf474a0..263c9a9b0e 100644
--- a/pkg/querier/tripperware/roundtrip_test.go
+++ b/pkg/querier/tripperware/roundtrip_test.go
@@ -221,6 +221,7 @@ func TestRoundTrip(t *testing.T) {
 				time.Minute,
 				tc.maxSubQuerySteps,
 				0,
+				false,
 			)
 			resp, err := tw(downstream).RoundTrip(req)
 			if tc.expectedErr == nil {