diff --git a/.changeset/five-phones-enjoy.md b/.changeset/five-phones-enjoy.md
new file mode 100644
index 000000000..393904632
--- /dev/null
+++ b/.changeset/five-phones-enjoy.md
@@ -0,0 +1,5 @@
+---
+"@solana/rpc-api": patch
+---
+
+Expanded the type of several RPC inputs to accept readonly arrays of values
diff --git a/packages/rpc-api/src/getBlockCommitment.ts b/packages/rpc-api/src/getBlockCommitment.ts
index 61c51aa7f..e636f0f19 100644
--- a/packages/rpc-api/src/getBlockCommitment.ts
+++ b/packages/rpc-api/src/getBlockCommitment.ts
@@ -5,7 +5,7 @@ type GetBlockCommitmentApiResponse = Readonly<{
      * An array that represents the amount of cluster stake, denominated in {@link Lamports}, that
      * has voted on the block at each depth from `0` to `MAX_LOCKOUT_HISTORY`.
      */
-    commitment: Lamports[] | null;
+    commitment: readonly Lamports[] | null;
     /** The total active stake, in {@link Lamports}, of the current epoch. */
     totalStake: Lamports;
 }>;
diff --git a/packages/rpc-api/src/getInflationReward.ts b/packages/rpc-api/src/getInflationReward.ts
index 56b45ec2f..ed4ed6fd2 100644
--- a/packages/rpc-api/src/getInflationReward.ts
+++ b/packages/rpc-api/src/getInflationReward.ts
@@ -46,5 +46,8 @@ export type GetInflationRewardApi = {
      *
      * @see https://solana.com/docs/rpc/http/getinflationreward
      */
-    getInflationReward(addresses: Address[], config?: GetInflationRewardApiConfig): GetInflationRewardApiResponse;
+    getInflationReward(
+        addresses: readonly Address[],
+        config?: GetInflationRewardApiConfig,
+    ): GetInflationRewardApiResponse;
 };
diff --git a/packages/rpc-api/src/getMultipleAccounts.ts b/packages/rpc-api/src/getMultipleAccounts.ts
index 94c0991f8..357b00e36 100644
--- a/packages/rpc-api/src/getMultipleAccounts.ts
+++ b/packages/rpc-api/src/getMultipleAccounts.ts
@@ -69,7 +69,7 @@ export type GetMultipleAccountsApi = {
      * @see https://solana.com/docs/rpc/http/getmultipleaccounts
      */
     getMultipleAccounts(
-        addresses: Address[],
+        addresses: readonly Address[],
         config: GetMultipleAccountsApiCommonConfig &
             GetMultipleAccountsApiSliceableCommonConfig &
             Readonly<{
@@ -89,7 +89,7 @@ export type GetMultipleAccountsApi = {
      * @see https://solana.com/docs/rpc/http/getmultipleaccounts
      */
     getMultipleAccounts(
-        addresses: Address[],
+        addresses: readonly Address[],
         config: GetMultipleAccountsApiCommonConfig &
             GetMultipleAccountsApiSliceableCommonConfig &
             Readonly<{
@@ -112,7 +112,7 @@ export type GetMultipleAccountsApi = {
      * @see https://solana.com/docs/rpc/http/getmultipleaccounts
      */
     getMultipleAccounts(
-        addresses: Address[],
+        addresses: readonly Address[],
         config: GetMultipleAccountsApiCommonConfig &
             Readonly<{
                 encoding: 'jsonParsed';
@@ -131,7 +131,7 @@ export type GetMultipleAccountsApi = {
      * @see https://solana.com/docs/rpc/http/getmultipleaccounts
      */
     getMultipleAccounts(
-        addresses: Address[],
+        addresses: readonly Address[],
         config: GetMultipleAccountsApiCommonConfig &
             GetMultipleAccountsApiSliceableCommonConfig &
             Readonly<{
@@ -150,7 +150,7 @@ export type GetMultipleAccountsApi = {
      * @see https://solana.com/docs/rpc/http/getmultipleaccounts
      */
     getMultipleAccounts(
-        addresses: Address[],
+        addresses: readonly Address[],
         config?: GetMultipleAccountsApiCommonConfig,
     ): SolanaRpcResponse<(GetMultipleAccountsApiResponseBase & (AccountInfoWithBase64EncodedData | null))[]>;
 };
diff --git a/packages/rpc-api/src/getProgramAccounts.ts b/packages/rpc-api/src/getProgramAccounts.ts
index 47a8fd3ee..583a514a7 100644
--- a/packages/rpc-api/src/getProgramAccounts.ts
+++ b/packages/rpc-api/src/getProgramAccounts.ts
@@ -51,7 +51,7 @@ type GetProgramAccountsApiCommonConfig = Readonly<{
      *
      * @defaultValue When omitted, no filters are applied.
      */
-    filters?: (GetProgramAccountsDatasizeFilter | GetProgramAccountsMemcmpFilter)[];
+    filters?: readonly (GetProgramAccountsDatasizeFilter | GetProgramAccountsMemcmpFilter)[];
     /**
      * Prevents accessing stale data by enforcing that the RPC node has processed transactions up to
      * this slot
diff --git a/packages/rpc-api/src/getRecentPrioritizationFees.ts b/packages/rpc-api/src/getRecentPrioritizationFees.ts
index 56bf1fcfb..69dc21b1e 100644
--- a/packages/rpc-api/src/getRecentPrioritizationFees.ts
+++ b/packages/rpc-api/src/getRecentPrioritizationFees.ts
@@ -24,5 +24,5 @@ export type GetRecentPrioritizationFeesApi = {
      *
      * @see https://solana.com/docs/rpc/http/getrecentprioritizationfees
      */
-    getRecentPrioritizationFees(addresses?: Address[]): GetRecentPrioritizationFeesApiResponse;
+    getRecentPrioritizationFees(addresses?: readonly Address[]): GetRecentPrioritizationFeesApiResponse;
 };
diff --git a/packages/rpc-api/src/getSignatureStatuses.ts b/packages/rpc-api/src/getSignatureStatuses.ts
index 802641076..adf75511c 100644
--- a/packages/rpc-api/src/getSignatureStatuses.ts
+++ b/packages/rpc-api/src/getSignatureStatuses.ts
@@ -46,7 +46,7 @@ export type GetSignatureStatusesApi = {
          * An array of transaction signatures to confirm, as base-58 encoded strings (up to a
          * maximum of 256)
          */
-        signatures: Signature[],
+        signatures: readonly Signature[],
         config?: Readonly<{
             /**
              * Determines whether the search for a transaction with a given signature will consider
diff --git a/packages/rpc-api/src/simulateTransaction.ts b/packages/rpc-api/src/simulateTransaction.ts
index 439a6a5e2..9ebf591cd 100644
--- a/packages/rpc-api/src/simulateTransaction.ts
+++ b/packages/rpc-api/src/simulateTransaction.ts
@@ -64,7 +64,7 @@ type SigVerifyAndReplaceRecentBlockhashConfig<TReplaceBlockhash extends boolean
 type AccountsConfigWithBase64EncodingZstdCompression = Readonly<{
     accounts: {
         /** An `array` of accounts to return */
-        addresses: Address[];
+        addresses: readonly Address[];
         /** Encoding for returned Account data */
         encoding: 'base64+zstd';
     };
@@ -73,7 +73,7 @@ type AccountsConfigWithBase64EncodingZstdCompression = Readonly<{
 type AccountsConfigWithJsonParsedEncoding = Readonly<{
     accounts: {
         /** An `array` of accounts to return */
-        addresses: Address[];
+        addresses: readonly Address[];
         /** Encoding for returned Account data */
         encoding: 'jsonParsed';
     };
@@ -82,7 +82,7 @@ type AccountsConfigWithJsonParsedEncoding = Readonly<{
 type AccountsConfigWithBase64Encoding = Readonly<{
     accounts: {
         /** An `array` of accounts to return */
-        addresses: Address[];
+        addresses: readonly Address[];
         // Optional because this is the default encoding
         /** Encoding for returned Account data */
         encoding?: 'base64';