Bradford West MP Naz Shah's suspension from the Labour Party has been lifted.
Ms Shah was stripped of the parliamentary whip in April over comments about Israel she made online, including one suggesting Israel should be moved to the United States.
In a Commons statement she said she "regretted" the posts, which were made in 2014 before she became an MP.
She was reinstated following a meeting of the party's National Executive Committee earlier on Tuesday.
She was given a formal warning, told to apologise for bringing the party into disrepute and warned that if there was another incident she would be expelled.
Ms Shah also quit her role as a Parliamentary assistant to shadow chancellor John McDonnell after the comments came to light.
Apologising in the Commons, she said: "Anti-Semitism is racism, full stop. As an MP I will do everything in my power to build relationships between Muslims, Jews and people of different faiths and none."
The comments triggered a wider row over alleged anti-Semitism within the party and Labour leader Jeremy Corbyn has faced criticism for his handling of anti-Semitism rows that have engulfed the party in recent months.
Appearing before the Commons Home Affairs Committee on Monday, he condemned Ken Livingstone's controversial claims that Adolf Hitler initially backed Zionism, which the former London mayor made amid the row over Ms Shah's comments.
Mr Livingstone, who was suspended as a result of his comments, has had his case referred to Labour's National Constitutional Committee.