diff --git a/src/core/diags/README.md b/src/core/diags/README.md
index 550223d02..9ec39c2cf 100644
--- a/src/core/diags/README.md
+++ b/src/core/diags/README.md
@@ -80,12 +80,13 @@ Done
 
 ### diag frame
 
-Usage: `diag frame [-c] [-s] <frame>`
+Usage: `diag frame [-c] [-p TX_POWER] [-s] <frame>`
 
 Set the frame (hex encoded) to be used by `diag send` and `diag repeat`. The frame may be overwritten by `diag send` and `diag repeat`.
 
 - Specify `-s` to indicate that tx security is already processed so that it should be skipped in the radio layer.
 - Specify `-c` to enable CSMA/CA for this frame in the radio layer.
+- Specify `-p` to specify the tx power in dBm for this frame.
 
 ```bash
 > diag frame 11223344
diff --git a/src/core/diags/factory_diags.cpp b/src/core/diags/factory_diags.cpp
index e17cae27c..ab88579f3 100644
--- a/src/core/diags/factory_diags.cpp
+++ b/src/core/diags/factory_diags.cpp
@@ -232,6 +232,7 @@ Error Diags::ProcessFrame(uint8_t aArgsLength, char *aArgs[])
     uint16_t size              = OT_RADIO_FRAME_MAX_SIZE;
     bool     securityProcessed = false;
     bool     csmaCaEnabled     = false;
+    int8_t   txPower           = OT_RADIO_POWER_INVALID;
 
     while (aArgsLength > 1)
     {
@@ -239,6 +240,17 @@ Error Diags::ProcessFrame(uint8_t aArgsLength, char *aArgs[])
         {
             securityProcessed = true;
         }
+        else if (StringMatch(aArgs[0], "-p"))
+        {
+            long value;
+
+            aArgs++;
+            aArgsLength--;
+
+            VerifyOrExit(aArgsLength > 1, error = kErrorInvalidArgs);
+            SuccessOrExit(error = ParseLong(aArgs[0], value));
+            txPower = static_cast<int8_t>(value);
+        }
         else if (StringMatch(aArgs[0], "-c"))
         {
             csmaCaEnabled = true;
@@ -261,6 +273,7 @@ Error Diags::ProcessFrame(uint8_t aArgsLength, char *aArgs[])
     ResetTxPacket();
     mTxPacket->mInfo.mTxInfo.mCsmaCaEnabled       = csmaCaEnabled;
     mTxPacket->mInfo.mTxInfo.mIsSecurityProcessed = securityProcessed;
+    mTxPacket->mInfo.mTxInfo.mTxPower             = txPower;
     mTxPacket->mLength                            = size;
     mIsTxPacketSet                                = true;
 
diff --git a/tests/scripts/expect/cli-diags.exp b/tests/scripts/expect/cli-diags.exp
index 6f2a3f192..116412f8c 100755
--- a/tests/scripts/expect/cli-diags.exp
+++ b/tests/scripts/expect/cli-diags.exp
@@ -166,6 +166,13 @@ send "diag send 1\n"
 expect "length 0x3"
 expect "Done"
 
+send_user "send frame with tx power\n"
+send "diag frame -p 11 112233\n"
+expect "Done"
+send "diag send 1\n"
+expect "length 0x3"
+expect "Done"
+
 send "diag repeat stop\n"
 expect "Done"