diff --git a/include/openthread/cli.h b/include/openthread/cli.h
index 5a8f54c43..c13657796 100644
--- a/include/openthread/cli.h
+++ b/include/openthread/cli.h
@@ -92,11 +92,10 @@ void otCliConsoleInit(otInstance *aInstance, otCliConsoleOutputCallback aCallbac
 /**
  * This method is called to feed in a console input line.
  *
- * @param[in]  aBuf        A pointer to a buffer with an input.
- * @param[in]  aBufLength  A length of the input data stored in the buffer.
+ * @param[in]  aBuf        A pointer to a null-terminated string.
  *
  */
-void otCliConsoleInputLine(char *aBuf, uint16_t aBufLength);
+void otCliConsoleInputLine(char *aBuf);
 
 /**
  * Initialize the CLI UART module.
diff --git a/include/openthread/instance.h b/include/openthread/instance.h
index b0297f6d9..8f92ab4bd 100644
--- a/include/openthread/instance.h
+++ b/include/openthread/instance.h
@@ -53,7 +53,7 @@ extern "C" {
  * @note This number versions both OpenThread platform and user APIs.
  *
  */
-#define OPENTHREAD_API_VERSION (82)
+#define OPENTHREAD_API_VERSION (83)
 
 /**
  * @addtogroup api-instance
diff --git a/src/cli/cli.cpp b/src/cli/cli.cpp
index 16eecdcc7..6e2bafd0c 100644
--- a/src/cli/cli.cpp
+++ b/src/cli/cli.cpp
@@ -4783,17 +4783,17 @@ otError Interpreter::ProcessDiag(uint8_t aArgsLength, char *aArgs[])
 }
 #endif
 
-void Interpreter::ProcessLine(char *aBuf, uint16_t aBufLength)
+void Interpreter::ProcessLine(char *aBuf)
 {
     char *         args[kMaxArgs] = {nullptr};
     uint8_t        argsLength;
     const Command *command;
 
-    VerifyOrExit(aBuf != nullptr && StringLength(aBuf, aBufLength + 1) <= aBufLength);
+    VerifyOrExit(aBuf != nullptr && StringLength(aBuf, kMaxLineLength) <= kMaxLineLength - 1);
 
     VerifyOrExit(Utils::CmdLineParser::ParseCmd(aBuf, argsLength, args, kMaxArgs) == OT_ERROR_NONE,
                  OutputLine("Error: too many args (max %d)", kMaxArgs));
-    VerifyOrExit(argsLength >= 1, OutputLine("Error: no given command."));
+    VerifyOrExit(argsLength >= 1);
 
 #if OPENTHREAD_CONFIG_DIAG_ENABLE
     VerifyOrExit((!otDiagIsEnabled(mInstance) || (strcmp(args[0], "diag") == 0)),
diff --git a/src/cli/cli.hpp b/src/cli/cli.hpp
index ae1cb4f48..9a8a8ae75 100644
--- a/src/cli/cli.hpp
+++ b/src/cli/cli.hpp
@@ -125,10 +125,9 @@ public:
      * This method interprets a CLI command.
      *
      * @param[in]  aBuf        A pointer to a string.
-     * @param[in]  aBufLength  The length of the string in bytes.
      *
      */
-    void ProcessLine(char *aBuf, uint16_t aBufLength);
+    void ProcessLine(char *aBuf);
 
     /**
      * This method delivers raw characters to the client.
diff --git a/src/cli/cli_config.h b/src/cli/cli_config.h
index 265ed16d2..16976bb4f 100644
--- a/src/cli/cli_config.h
+++ b/src/cli/cli_config.h
@@ -44,7 +44,7 @@
  *
  */
 #ifndef OPENTHREAD_CONFIG_CLI_MAX_LINE_LENGTH
-#define OPENTHREAD_CONFIG_CLI_MAX_LINE_LENGTH 128
+#define OPENTHREAD_CONFIG_CLI_MAX_LINE_LENGTH 384
 #endif
 
 /**
diff --git a/src/cli/cli_console.cpp b/src/cli/cli_console.cpp
index 55ef6bfeb..ab7f7499d 100644
--- a/src/cli/cli_console.cpp
+++ b/src/cli/cli_console.cpp
@@ -53,9 +53,9 @@ extern "C" void otCliConsoleInit(otInstance *aInstance, otCliConsoleOutputCallba
     Console::Initialize(aInstance, aCallback, aContext);
 }
 
-extern "C" void otCliConsoleInputLine(char *aBuf, uint16_t aBufLength)
+extern "C" void otCliConsoleInputLine(char *aBuf)
 {
-    Interpreter::GetInterpreter().ProcessLine(aBuf, aBufLength);
+    Interpreter::GetInterpreter().ProcessLine(aBuf);
 }
 
 // Add stubs for simulation
diff --git a/src/cli/cli_uart.cpp b/src/cli/cli_uart.cpp
index da408b015..4b573a020 100644
--- a/src/cli/cli_uart.cpp
+++ b/src/cli/cli_uart.cpp
@@ -227,7 +227,7 @@ otError Uart::ProcessCommand(void)
 #endif
     if (mRxLength > 0)
     {
-        ProcessLine(mRxBuffer, mRxLength);
+        ProcessLine(mRxBuffer);
     }
 
     mRxLength = 0;
diff --git a/src/posix/console_cli.cpp b/src/posix/console_cli.cpp
index 18fa1909f..b98ea8851 100644
--- a/src/posix/console_cli.cpp
+++ b/src/posix/console_cli.cpp
@@ -70,12 +70,10 @@ static void InputCallback(char *aLine)
 {
     if (aLine != nullptr)
     {
-        size_t len;
-
-        if ((len = strlen(aLine)) > 0)
+        if (aLine[0] != '\0')
         {
             add_history(aLine);
-            otCliConsoleInputLine(aLine, (uint16_t)len);
+            otCliConsoleInputLine(aLine);
         }
         free(aLine);
     }