Cruddas was selected to be the prospective parliamentary candidate for the safe Labour seat of Dagenham in 2000, after the sitting MP Judith Church announced that she would be retiring.
He was elected as the MP for Dagenham the following year at the 2001 general election, with a majority of 8,693 votes.

From the backbenches, Cruddas quickly became a vocal critic of the government for what he saw as their ignoring of their traditional, working-class support in a bid to be more appealing to middle-class voters.
He rebelled against the government on a number of occasions; including on the introduction of university top-up fees, the legislation on asylum seekers, the introduction of trust schools, proposals to renew the UK Trident nuclear weapons system, and foundation trusts.
He supported both the Fourth Option for direct investment in council housing and the Trade Union Freedom Bill.

Cruddas was re-elected at the 2005 general election, but his Dagenham constituency was abolished in boundary changes for the 2010 general election.
Cruddas chose to contest the newly created constituency of Dagenham and Rainham, which was notionally marginal.
He won the seat by 2,630 votes in a close-run election campaign, which was a seat that the British National Party had heavily targeted.
This resulted in a large number of anti-fascist organisations not affiliated to the Labour Party, such as Hope not Hate, campaigning for Cruddas to resist the BNP.
After being successfully elected, he took up a part-time position teaching Labour history at University College, Oxford from 2010–12.
Cruddas was selected to be the prospective parliamentary candidate for the safe Labour seat of Dagenham in 2000, after the sitting MP Judith Church announced that she would be retiring. He was elected as the MP for Dagenham the following year at the 2001 general election, with a majority of 8,693 votes.
From the backbenches, Cruddas quickly became a vocal critic of the government for what he saw as their ignoring of their traditional, working-class support in a bid to be more appealing to middle-class voters. He rebelled against the government on a number of occasions; including on the introduction of university top-up fees, the legislation on asylum seekers, the introduction of trust schools, proposals to renew the UK Trident nuclear weapons system, and foundation trusts. He supported both the Fourth Option for direct investment in council housing and the Trade Union Freedom Bill.
Cruddas was re-elected at the 2005 general election, but his Dagenham constituency was abolished in boundary changes for the 2010 general election. Cruddas chose to contest the newly created constituency of Dagenham and Rainham, which was notionally marginal. He won the seat by 2,630 votes in a close-run election campaign, which was a seat that the British National Party had heavily targeted. This resulted in a large number of anti-fascist organisations not affiliated to the Labour Party, such as Hope not Hate, campaigning for Cruddas to resist the BNP. After being successfully elected, he took up a part-time position teaching Labour history at University College, Oxford from 2010–12.
Jon Cruddas