The 33-year-old reality TV star and the 36-year-old rocker, who have daughter Harlow, eight, and son Sparrow, seven, have listed their four-bedroom, five-bathroom estate in Laurel Canyon for $3.49 million.
The lavish property, which the former 'Simple Life' star purchased in 2009 for $1.91 million, features an ''extensively remodelled'' living space, a pool-side guest house and a spacious kitchen, according to Variety.com.
Both couples are extremely close and Nicole previously claimed she was responsible for setting her brother-in-law up with Cameron just seven months before they tied the knot in January.
She said: ''Yes. I'm going to take responsibility for everything! I approve of anything that's going to make Benji happy.
''I am a devoted sister-in-law. I'm happy for anyone who is happy, and I want everyone to be surrounded with love.''
Joel sold his former bachelor pad in Glendale last June.