Labour MP Clive Lewis has been cleared of groping a woman due to "insufficient evidence".
Mr Lewis was accused last month of squeezing the woman's bottom while giving her a hug at an event at the Labour annual conference in Brighton in September.
The Norwich South MP denied the allegation, and said he was now "very pleased to be able to put this behind me and move on".
The former shadow defence secretary was the most high profile Labour politician to be caught up in the wave of allegations of sexual harassment and inappropriate behaviour which has rocked Westminster in recent weeks.
Announcing the conclusion of the case, opened after a formal complaint was brought against Mr Lewis by the unnamed woman, a Labour Party spokesman said: "After consideration of statements provided by the complainant and the respondent, the National Executive Committee's sexual harassment panel has ruled that on the balance of the evidence the matter should not be referred to a full hearing of the National Constitutional Committee."
Mr Lewis said: "I am very pleased to be able to put this behind me and move on.
"I believe it right and proper the Labour Party treats all allegations of bullying, harassment and sexual misconduct seriously.
"I want to express my gratitude to my wife, friends and constituents who have supported me during recent weeks.
"I look forward very much to continuing my work in Parliament, fighting for the people I represent and the city I love."
The investigation into Mr Lewis came shortly after he was the target of criticism over a video, reportedly filmed at the same event at the Momentum-backed festival The World Transformed, in which he jokingly told a man to "get on your knees bitch".
His comments in the video drew widespread condemnation from fellow Labour MPs, with party leader Jeremy Corbyn describing them as "completely unacceptable".