diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7559c61ffda5..193dea1b302b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -90,6 +90,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [#14406](https://github.com/cosmos/cosmos-sdk/issues/14406) Migrate usage of types/store.go to store/types/..
 * (x/staking) [#14590](https://github.com/cosmos/cosmos-sdk/pull/14590) Return undelegate amount in MsgUndelegateResponse
 * (baseapp) [#15023](https://github.com/cosmos/cosmos-sdk/pull/15023) & [#15213](https://github.com/cosmos/cosmos-sdk/pull/15213) Add `MessageRouter` interface to baseapp and pass it to authz, gov and groups instead of concrete type. 
+* (simapp) [#15305](https://github.com/cosmos/cosmos-sdk/pull/15305) Add `AppStateFnWithExtendedCb` with callback function to extend rawState.
 
 ### State Machine Breaking
 
diff --git a/testutil/sims/state_helpers.go b/testutil/sims/state_helpers.go
index 7143ebfbb017..7b97cb6160cf 100644
--- a/testutil/sims/state_helpers.go
+++ b/testutil/sims/state_helpers.go
@@ -33,6 +33,20 @@ const (
 // If a file is not given for the genesis or the sim params, it creates a randomized one.
 // genesisState is the default genesis state of the whole app.
 func AppStateFn(cdc codec.JSONCodec, simManager *module.SimulationManager, genesisState map[string]json.RawMessage) simtypes.AppStateFn {
+	return AppStateFnWithExtendedCb(cdc, simManager, genesisState, nil)
+}
+
+// AppStateFnWithExtendedCb returns the initial application state using a genesis or the simulation parameters.
+// It panics if the user provides files for both of them.
+// If a file is not given for the genesis or the sim params, it creates a randomized one.
+// genesisState is the default genesis state of the whole app.
+// cb is the callback function to extend rawState.
+func AppStateFnWithExtendedCb(
+	cdc codec.JSONCodec,
+	simManager *module.SimulationManager,
+	genesisState map[string]json.RawMessage,
+	cb func(rawState map[string]json.RawMessage),
+) simtypes.AppStateFn {
 	return func(
 		r *rand.Rand,
 		accs []simtypes.Account,
@@ -137,6 +151,11 @@ func AppStateFn(cdc codec.JSONCodec, simManager *module.SimulationManager, genes
 		rawState[stakingtypes.ModuleName] = cdc.MustMarshalJSON(stakingState)
 		rawState[banktypes.ModuleName] = cdc.MustMarshalJSON(bankState)
 
+		// extend state from callback function
+		if cb != nil {
+			cb(rawState)
+		}
+
 		// replace appstate
 		appState, err = json.Marshal(rawState)
 		if err != nil {
diff --git a/types/simulation/types.go b/types/simulation/types.go
index 34d29d04e323..56d496e03b0e 100644
--- a/types/simulation/types.go
+++ b/types/simulation/types.go
@@ -177,6 +177,11 @@ type AppStateFn func(r *rand.Rand, accs []Account, config Config) (
 	appState json.RawMessage, accounts []Account, chainId string, genesisTimestamp time.Time,
 )
 
+// AppStateFnWithExtendedCb returns the app state json bytes and the genesis accounts
+type AppStateFnWithExtendedCb func(r *rand.Rand, accs []Account, config Config) (
+	appState json.RawMessage, accounts []Account, chainId string, genesisTimestamp time.Time,
+)
+
 // RandomAccountFn returns a slice of n random simulation accounts
 type RandomAccountFn func(r *rand.Rand, n int) []Account