The Independent Group for Change is being disbanded after failing to win any seats at the general election, leader Anna Soubry has said.
The party was founded last March by Labour and Tory MPs unhappy with the direction their parties were going in.
The 11 MPs aimed to create a new centre ground force in politics.
But some left to join the Lib Dems, quit politics or run as independents, and the remaining three lost to candidates from their former parties.
Eight Labour MPs left the party to form the breakaway group, citing Labour's Brexit policy and record on tackling anti-Semitism.
They were later joined by three Remain-supporting Conservative MPs, Anna Soubry, Sarah Wollaston and Heidi Allen.
Dr Wollaston later joined the Lib Dems - and lost her seat to a Tory candidate last Thursday - and Ms Allen did not stand for re-election.
Former Labour MPs Chuka Umunna and Luciana Berger stood as Liberal Democrat candidates but were also defeated in last Thursday's election.
Independent Group for Change leader Ms Soubry came a distant third in Broxtowe, which was won by the Conservative candidate.
Former Labour MPs Chris Leslie and Mike Gapes, who stood as Independent Group for Change candidates, also lost their seats.
Gavin Shuker, who quit Labour to join Change UK before deciding to run as an independent in the Luton South poll, also failed to be elected.
Earlier on Thursday, the group, which was briefly known as Change UK, tweeted: "We came together & took a stand when others wouldn't.
"It was right to shine a spotlight on Britain's broken politics. But having taken stock and with no voice now in Parliament, we begin the process of winding up our party. Thanks to all who stood with us."
In a statement to members, Ms Soubry said the party's failure to make an impact at May's European elections, and the subsequent defection or retirement of most of its MPs, made it "harder for us to cut through as a distinctive political force in our own right".
But, she added, "we nevertheless believed it was important for us to have the courage of our convictions and to stand in the general election so that our constituents would have a full choice".
"Whilst there is clearly a need for massive change in British politics," Ms Soubry went on, "now that we no longer have voices within Parliament, a longer-term realignment will have to take place in a different way.
"Honesty and realism are at the core of our values, and we therefore must recognise that the political uncertainty of recent months has now given way to a settled pattern in Parliament for the next five years. So this is the right time for us to take stock."