The US pop sensation, 18, shot to worldwide fame after the release of the global hit last January, which topped the charts in the UK and US.
The track went on to win Song of the Year at the MTV Video Music Awards and the Apple Music Awards.
It has also been nominated for Record of the Year at the 2022 Grammy Awards alongside global superstars including Abba, Billie Eilish and Lil Nas X.
Rodrigo shared a black-and-white video to Instagram of her singing the opening of the track and said it had been recorded days after she first wrote the mega-hit.
She wrote: "Happy first birthday to the little song that changed my whole life.
"I made this video a day or two after I wrote drivers license in my living room (with a very squeaky sustain pedal lol).
"Crazy to think how quickly life changes.
"Thank u to everyone who has supported me so tenderly.
"Music is the most magical thing in the world."
The singer, who previously acted in the Disney+ series High School Musical: The Musical – The Series, first made headlines when the track went viral online with the help of TikTok and claims of a potential love triangle among her Disney co-stars being the inspiration for the song.
In Rodrigo's song, she sings about her heartbreak over a break-up and refers to a "blonde girl" who is "so much older than me", and "everything I'm insecure about".
Rumours swirled online about a love triangle between Rodrigo, her High School Musical co-star Joshua Bassett, 21, and actress Sabrina Carpenter, 22, best known for starring in the Disney series Girl Meets World.
However, Rodrigo rose above the speculation and continued to have a breakout year, with her follow-up singles deja vu and good 4 u also enjoying incredible success.
Her debut album Sour also topped the charts in the UK and US and won Album of the Year at the Apple Music Awards and People's Choice Awards, with another pending nomination from the Grammy Awards.
The singer has been named Time magazine's Entertainer Of The Year in 2021.