diff --git a/include/openthread/message.h b/include/openthread/message.h
index 879eb3612..3e0177850 100644
--- a/include/openthread/message.h
+++ b/include/openthread/message.h
@@ -142,7 +142,7 @@ void otMessageFree(otMessage *aMessage);
  * @sa otMessageSetLength
  *
  */
-uint16_t otMessageGetLength(otMessage *aMessage);
+uint16_t otMessageGetLength(const otMessage *aMessage);
 
 /**
  * Set the message length in bytes.
@@ -180,7 +180,7 @@ otError otMessageSetLength(otMessage *aMessage, uint16_t aLength);
  * @sa otMessageWrite
  *
  */
-uint16_t otMessageGetOffset(otMessage *aMessage);
+uint16_t otMessageGetOffset(const otMessage *aMessage);
 
 /**
  * Set the message offset in bytes.
@@ -211,7 +211,7 @@ otError otMessageSetOffset(otMessage *aMessage, uint16_t aOffset);
  * @retval FALSE  If link security is not enabled.
  *
  */
-bool otMessageIsLinkSecurityEnabled(otMessage *aMessage);
+bool otMessageIsLinkSecurityEnabled(const otMessage *aMessage);
 
 /**
  * This function sets/forces the message to be forwarded using direct transmission.
@@ -230,7 +230,7 @@ void otMessageSetDirectTransmission(otMessage *aMessage, bool aEnabled);
  * @returns The average RSS value (in dBm) or OT_RADIO_RSSI_INVALID if no average RSS is available.
  *
  */
-int8_t otMessageGetRss(otMessage *aMessage);
+int8_t otMessageGetRss(const otMessage *aMessage);
 
 /**
  * Append bytes to a message.
@@ -272,7 +272,7 @@ otError otMessageAppend(otMessage *aMessage, const void *aBuf, uint16_t aLength)
  * @sa otMessageWrite
  *
  */
-int otMessageRead(otMessage *aMessage, uint16_t aOffset, void *aBuf, uint16_t aLength);
+int otMessageRead(const otMessage *aMessage, uint16_t aOffset, void *aBuf, uint16_t aLength);
 
 /**
  * Write bytes to a message.
diff --git a/src/core/api/message_api.cpp b/src/core/api/message_api.cpp
index 99e9718c5..274f9db4c 100644
--- a/src/core/api/message_api.cpp
+++ b/src/core/api/message_api.cpp
@@ -44,9 +44,9 @@ void otMessageFree(otMessage *aMessage)
     static_cast<Message *>(aMessage)->Free();
 }
 
-uint16_t otMessageGetLength(otMessage *aMessage)
+uint16_t otMessageGetLength(const otMessage *aMessage)
 {
-    Message &message = *static_cast<Message *>(aMessage);
+    const Message &message = *static_cast<const Message *>(aMessage);
     return message.GetLength();
 }
 
@@ -56,9 +56,9 @@ otError otMessageSetLength(otMessage *aMessage, uint16_t aLength)
     return message.SetLength(aLength);
 }
 
-uint16_t otMessageGetOffset(otMessage *aMessage)
+uint16_t otMessageGetOffset(const otMessage *aMessage)
 {
-    Message &message = *static_cast<Message *>(aMessage);
+    const Message &message = *static_cast<const Message *>(aMessage);
     return message.GetOffset();
 }
 
@@ -68,9 +68,9 @@ otError otMessageSetOffset(otMessage *aMessage, uint16_t aOffset)
     return message.SetOffset(aOffset);
 }
 
-bool otMessageIsLinkSecurityEnabled(otMessage *aMessage)
+bool otMessageIsLinkSecurityEnabled(const otMessage *aMessage)
 {
-    Message &message = *static_cast<Message *>(aMessage);
+    const Message &message = *static_cast<const Message *>(aMessage);
     return message.IsLinkSecurityEnabled();
 }
 
@@ -88,9 +88,9 @@ void otMessageSetDirectTransmission(otMessage *aMessage, bool aEnabled)
     }
 }
 
-int8_t otMessageGetRss(otMessage *aMessage)
+int8_t otMessageGetRss(const otMessage *aMessage)
 {
-    Message &message = *static_cast<Message *>(aMessage);
+    const Message &message = *static_cast<const Message *>(aMessage);
     return message.GetAverageRss();
 }
 
@@ -100,9 +100,9 @@ otError otMessageAppend(otMessage *aMessage, const void *aBuf, uint16_t aLength)
     return message.Append(aBuf, aLength);
 }
 
-int otMessageRead(otMessage *aMessage, uint16_t aOffset, void *aBuf, uint16_t aLength)
+int otMessageRead(const otMessage *aMessage, uint16_t aOffset, void *aBuf, uint16_t aLength)
 {
-    Message &message = *static_cast<Message *>(aMessage);
+    const Message &message = *static_cast<const Message *>(aMessage);
     return message.Read(aOffset, aLength, aBuf);
 }