The X Factor judge looked delighted as a two-tier cream cake was carried over to him, accompanied by his son Eric and Terri Seymour's daughter Coco, who danced while singing Happy Birthday to the music mogul.
However, Eric was left surprised after being told that he wouldn't be able to eat any of the decadent treat.
VIDEO: Simon Cowell's son Eric has a surprise reaction to his dad's birthday cake
"This is the second cake that you aren't allowed to eat," Eric's mum, Lauren Silverman, told the little boy. "We're not allowed?!" Eric exclaimed, before Lauren added: "Yes, we didn't think about that."
Despite not being able to have any of the cake, it looked like Eric still had a wonderful time celebrating his dad's birthday.
Simon looked in good spirits in the footage, dressed in a navy suit, as he continues to recover from a broken back.
Simon Cowell's birthday cake at his low-key party
The music mogul fell off his electric bike in August, and has been keeping a low profile ever since as he recovers at home in Malibu.
Simon has round-the-clock care and is determined to make a full recovery. Most recently, the 61-year-old's friend, Amanda Holden, gave fans an update on his progress during an appearance on Loose Women.
Simon's son Eric and partner Lauren Silverman are taking care of him in Malibu
The Britain's Got Talent judge revealed that she was certain that Simon would be back on TV in the near future, and admitted to missing him on BGT, revealing that there was a "lack of silliness" without him.
The music mogul is recovering from a broken back
Simon's friend Sinitta also recently gave fans an update on his condition. "It was a serious accident. So for people who love him, like me, it was very, very scary," she told Entertainment Daily.
"He's taken some steps, so he has reassured himself that he's not paralysed. But he's got to take his time and get well."
Eric is keeping his dad's spirits up
After breaking his back, Simon 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."
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