New mum Lauren Silverman looked radiant and little Eric slept soundly even as camera shutters rattled around him.
Simon could be seen smiling and joking as he helped load baby Eric into the back of the waiting car. And although his expression was less overjoyed as he made his way through a swarm of paparazzi, he acknowledged their shouted congratulations with a polite: "Thank you very much."
Cowell might have made waves with his declarations that he isn't interested in changing nappies or midnight feeds, but here he appears every inch the hands-on dad.
The Lenox Hill Hospital, on Manhattan's Upper East Side, is a favourite location for celebrity mums-to-be. Among those who have given birth there are Beyoncé, Sarah Jessica Parker, Joan Rivers and Tina Fey.
From the hospital, the couple and their newborn checked into the St Regis hotel.