Former Labour MP Luciana Berger is to fight the seat of Finchley and Golders Green in north London for the Liberal Democrats at the next election.
She has chosen not to contest her current seat, Liverpool Wavertree, which she has represented since 2010.
Ms Berger quit Labour in February, blaming a culture of anti-Semitism in the party and personal attacks on her.
The Lib Dems came third in the London seat in 2017, but hope to do better due to their Brexit opposition.
The Jewish MP was a founding member of the Change UK party which launched in the run-up to the European Parliament elections in May.
However, she quit the party after its poor performance and joined the Lib Dems earlier this month.
In a letter addressed to her Liverpool Wavertree constituents posted on Twitter, Ms Berger says she made the decision with her husband, with whom she has two children.
"Balancing personal and and professional responsibilities is complicated for everyone," she writes.
"As a family, we have had to make a decision about how best to navigate work and raising our young children."
She adds they had decided to move to London after the next general election "after a great deal of thought".
In a statement, Liverpool Wavertree Lib Dems said they regretted her decision to contest a different seat but "understood the reasons for doing so".
Richard Kemp, who leads the Liberal Democrat group on Liverpool Council, said Ms Berger had been subject to "appalling anti-Semitism and gender bullying" during her time representing Labour in the constituency.
She has spoken of receiving thousands of anti-Semitic taunts online, as well as death threats.
An internet troll who sent anti-Semitic messages to Ms Berger and other victims was jailed for more than two years in 2017.
Liverpool Wavertree has been regarded as a safe Labour seat since boundary changes in the 1990s. The Lib Dems came third with less than three 3,000 votes in 2017.
In contrast, Finchley and Golders Green is a marginal seat which has fluctuated between the Conservatives and Labour since it was created in 1997.
According to the UK Polling Report, the constituency has the largest Jewish population of any seat in the UK, with more than 20% of residents describing themselves as Jewish in the 2011 census. It is also a heavily pro-Remain constituency.
The Lib Dems had selected Clareine Enderby to contest the seat.
Under different boundaries, the constituency of Finchley was represented by former Conservative leader Margaret Thatcher for more than 30 years between 1959 and 1992.
Conservative Mike Freer retained the new seat with a 1,657 majority in 2017, an election in which the Liberal Democrats received only 3,463 votes.
Ms Berger's move follows that of her fellow Lib Dem Chuka Umunna, who has decided to fight the seat of the Cities of London and Westminster, rather than Streatham in south London, whose MP he has been since 2010.