The architect of the Tories' welfare reforms is to retire from the Government.
Lord Freud will leave his role as a Work and Pensions Minister at the end of December after the Queen approved his resignation, Downing Street said.
He has served in the Department for Work and Pensions since David Cameron became Prime Minister in 2010.
Seen as one of the leading figures in the creation of the Government's flagship welfare reform, universal credit, he was promoted last year by Mr Cameron from a junior minister post to minister of state.
Lord Freud first recommended wide-ranging reforms to the benefits system in 2007 and was later recruited to the Government to push through his ideas.
Downing Street said a successor DWP minister in the House of Lords will be appointed "in due course".
The peer, who draws no ministerial salary, is the longest serving Government minister in the same role, and the only one remaining in the same job from Mr Cameron's first round of appointments in May 2010.
He attracted controversy in 2014 after suggesting some disabled workers are "not worth" the minimum wage but later apologised.
Announcing his retirement, Lord Freud said: "At the heart of our reforms is desire to give people independence to improve their lives.
"For too long, people have been trapped by a byzantine benefits system, leaving them powerless.
"This has always been my driving force - to give people back control over their own lives; to give support in times of need, but also to give a clear route out of the benefits system and into independence.
"That's what universal credit does, and I'm incredibly proud of what we have achieved. It's a testament to the support I've received both from my ministerial colleagues and civil servants in the DWP that we are now well on the way to achieving our goal of a truly modern, responsive welfare system which is already transforming lives.
"As I retire from my ministerial position, I leave with full confidence in the future of universal credit."
Work and Pensions Secretary Damian Green paid tribute to the peer.
"Everyone comes into government to make a difference, but David's contribution to transforming the welfare system has been outstanding," he said.
"As the architect of universal credit, he combines vision with an impressive attention to detail. Moreover, he cares greatly about improving the lives of some of the poorest people in our country.
"I want to thank him for everything has done over the years at DWP, and for all the help and support he has given to me and his ministerial colleagues. His will be a legacy of which he can be truly proud."
The Public and Commercial Services union said Lord Freud had been central to the injection of "poison" into the welfare system, which has suffered numerous spending cuts under the Tories.
A spokesman for the union said: "Among staff in DWP, unemployed, sick and disabled people, there'll be no mourning the loss of a man who injected poison into our social security system.
"For years Freud has been at the heart of the cruel and dangerous upheaval of our employment and benefits services, and we'll be glad to see the back of him."
Former chancellor George Osborne paid tribute to Lord Freud: "David Freud was one of the brains behind our reforms that delivered record levels of employment. Thank you, David."
SNP MP Alison Thewliss, who has campaigned against the Government's plans to limit tax credits to a family's first two children, said Lord Freud's departure from Government is a "very welcome development".
She said: "Lord Freud was without doubt one of the coldest, most heartless and ignorant politicians I've ever had the misfortune of dealing with in almost 10 years of elected politics."