Change UK has lost six of its 11 MPs following a disappointing performance in last month's EU elections, when it failed to get a single MEP elected.
The party announced that a new party leader, Anna Soubry, had been elected.
She said she was "deeply disappointed" that Heidi Allen, Chuka Umunna, Sarah Wollaston, Angela Smith, Luciana Berger and Gavin Shuker had left.
The departing MPs said they would be "returning to supporting each other as an independent grouping of MPs".
Change UK - formally known as the Independent Group - was formed earlier this year by MPs who quit Labour and the Conservatives.
A joint statement from the six outgoing members said they believed it was their priority now "to provide collegiate leadership to bring people together in the national interest".
"We know the landscape will continue to shift within the political environment and have concluded that by returning to sit as independents, we will be best placed to work cross-party and respond flexibly.
"We wish our colleagues well as they continue to build Change UK."
Shocked not shocked