LED On & Off

Jun 2026

Introduction

The Raspberry Pi Pico actually has an onboard LED that we can use for some simple Micro Python testing. Now one slight complication here is that the original Pico and the Pico 2 W use different ways to address the LED. This guide is using the Pico, where the LED is on GPIO pin 25. The way we will address the LED means that you don't really need to know the pin number.
In the above picture we can see where the LED is. Once powered on the LED by default will be off, and we will need to use some micro python to turn it on.
Lets run Thonny, and use some Micro Python code to turn on and turn off our onboard Pi Pico LED.
Here we can see the code that we need to enter in to Thonny.

# Import the picozero LED class from picozero import pico_led #Turn on the pico LED pico_led.on()

This code does a couple of things:
from picozero import pico_led

This line imports the pico_led object from the picozero library.
picozero is a beginner‑friendly library for controlling hardware on the Raspberry Pi Pico.
pico_led is a built‑in object that represents the on‑board LED (the little LED already on the Pico board).
So this line is basically saying: “Give me access to the Pico’s built‑in LED so I can control it.”

pico_led.on()

This is the line that actually turns the LED on.
pico_led is the LED object
.on() is a function that switches it on
The LED lights up and stays on until you turn it off or reset the board
It’s the simplest possible way to control hardware on the Pico.

Now that you have turned the LED on, you might want to turn it off, and the program is almost the same except for the argument for the pico_led line.

# Import the picozero LED class from picozero import pico_led #Turn on the pico LED pico_led.off()