The American Idol judge met up with his good friend Terri Seymour and her family, including daughter Coco, on Sunday, and was treated to a birthday cake with a special rendition of 'Happy Birthday' sung by his son Eric and Coco.
In footage shared on Terri's Instagram account, Eric and Coco danced over to the music mogul as they sang to him, much to Simon's delight.
VIDEO: Simon Cowell celebrates birthday with son Eric - with epic birthday cake
The X Factor judge then went on to blow out the candle on his cake, looking happy and relaxed as he sat at the table.
Simon turned 61 last week, and was inundated with messages from his fans and famous friends, including Amanda Holden, who sent him a bunch of flowers on his special day.
Simon Cowell was made a fuss of by son Eric and Coco at his birthday party
The star's presence was missed on Saturday night's Britain's Got Talent final, with Amanda paying tribute to her friend in a sweet Instagram post after the show.
Amanda is incredibly close to Simon and his partner Lauren Silverman, and took his place as head judge on BGT after his accident.
The music mogul has been recovering in Malibu with Eric and partner Lauren Silverman
The Heart Radio presenter appeared on Loose Women on Thursday to talk about the star's recovery, and revealed that she was hopeful that he would be back on TV again in the not so distant future.
"I miss Simon like crazy, I think Ashely [Banjo] is doing a brilliant job but there's a lack of silliness, let's say," she said.
The X Factor judge turned 61 last week, and Amanda also told the panel that she had sent him a birthday present, as well as a recovery gift when he first broke his back.
Simon broke his back at the beginning of August
"When he had the accident I sent him socks, Angel Delight, a book and Lego," she revealed, adding that for his birthday, she chose to send him flowers, so that Lauren could enjoy the benefits of them too.
When news emerged that Simon had broken his back, the dad-of-one reassured his fans that he was doing okay. "Some good advice… if you buy an electric trail bike, read the manual before you ride it for the first time," he tweeted.
"I have broken part of my back. Thank you to everyone for your kind messages."
Read more HELLO! US stories here
Like this story? Sign up to our newsletter to get other stories like this delivered straight to your inbox.