Sajid Javid has been named as the new home secretary after Amber Rudd's resignation.
Mr Javid, the son of a Pakistani bus driver whose family came to the UK in the 1960s, had been communities, local government and housing secretary.
Ms Rudd quit after "inadvertently misleading" MPs over what she knew about immigration removal targets.
It followed weeks of revelations about the treatment of Windrush families and criticism of government policy.
The Windrush generation settled legally in post-war Britain but their right-to-remain has been questioned, with some people having been detained, lost their jobs and been denied access to medical care.
This has prompted calls for the government to abandon its "hostile environment" policy on illegal immigration, which Ms Rudd and Prime Minister Theresa May have continued to defend.
Following Mr Javid's promotion, No 10 also announced former Northern Ireland secretary James Brokenshire will return to the cabinet as housing, communities and local government secretary.
At the weekend, Mr Javid told the Sunday Telegraph the Windrush scandal felt "very personal" to him as coming from a family of immigrants "it could have been me, my mum or my dad".
Mr Javid, a former investment banker and MP for Bromsgrove since 2010, has been communities secretary for about 18 months.
The 48-year old, who previously served as business and culture secretaries, led the government's response to last year's Grenfell Tower fire disaster.
He first entered Parliament in 2010 and supported remaining in the EU in the 2016 referendum despite being regarded as a Eurosceptic.