Lodewijk Frans Asscher was born on 27 September 1974 in Amsterdam in a mixed religious family; his father is of Jewish descent and his mother is Catholic. His father is a member of the People's Party for Freedom and Democracy and his mother a member of the Labour Party.
Asscher went to the Christelijk Gymnasium Sorghvliet in The Hague. He studied psychology (propaedeutics in 1995) and Dutch law (master's degree in 1998) at the University of Amsterdam in Amsterdam. In 2002, he received his PhD in law from the University of Amsterdam.
Asscher entered the city council after the Dutch municipal elections of 2002. Besides his role as the group leader of the Labour Party in the Amsterdam city council, he took part in the commission on General Affairs.
Until 1 January 2006, Asscher taught information law at the University of Amsterdam. In his book "New Amsterdam", Asscher advocated the eventual disappearance of the red light district. A few days after the release of the book, Asscher revoked that statement, stating that he was not against prostitution, but rather against sexual slavery.
After the Dutch municipal elections of 2006, where he led the Labour Party's campaign in Amsterdam, Asscher was installed as an alderman on 26 April. He served as alderman of Economics, Airport and Harbour, and deputy mayor of Amsterdam for the Labour Party from 2006 until 2010. And served as Acting Mayor of Amsterdam from 12 March 2010 to 7 July 2010. He then became alderman of Finances serving until 5 November 2012.
On 5 November 2012, he became Minister of Social Affairs and Employment and Deputy Prime Minister in the Cabinet Rutte II. In Amsterdam he was succeeded by Pieter Hilhorst (also PvdA).
In September 2014, Asscher announced heightened scrutiny of four Dutch Turkish organisations that he suspected of hindering integration, including a religious group, Millî Görüş. This led to the expulsion of 2 Dutch Turkish MPs from the Labour Party after they harshly criticised the move.
On 9 December 2016 Asscher won the leadership of the Labour Party in an election against Diederik Samsom. He obtained 54,5% of the vote.
Lodewijk Asscher is married to Jildau Piena, with whom he has three sons.