The reality TV mogul has placed the home in Beverly Hills, Los Angeles, on the market, which many see as him signalling the end of his single days as he prepares to settle down with his pregnant girlfriend Lauren Silverman.
A source told the Daily Mirror newspaper: "The house Simon has put on the market is the ultimate bachelor pad. It was designed to have fun in.
"The house has four huge bedrooms, stunning ocean and city views as well as an incredible swimming pool.
"Simon feels he no longer has a need for it now as he is settled with Lauren. He just can't wait for the baby to arrive.
"He has given very strict instructions on what he is looking for and Lauren is excitedly hunting for a place they can live in with the baby.
"He will of course still want huge mirrors in the new place though."
Simon has several properties across the world including a second house in Beverly Hills and a huge mansion in central London.
Meanwhile, Lauren brought Simon to Miami, Florida, to meet her mother over the past weekend, where they ate at Prime Italian's street-side terrace and were later overheard talking about property, prompting speculation Simon could buy a home in Florida.
A source told the New York Post newspaper: "They were talking about property as she was talking about the number of bedrooms they would need."