He arrives following the departure of Andy Homer to Shariah-compliant fellow challenger bank Gatehouse last month.
Oliver left Nationwide last year after 12 years with the building society, with Tanya Jospeh later confirmed as his successor. Oliver, latterly Nationwide head of external affairs, has since operated as a consultant.
Oliver starts today, reporting to Holly Marshall, director of corporate affairs.
Founded in 2009, Aldermore was acquired by South Africa's FirstRand Group in March this year. The bank lends to SMEs, individuals and landlords. As of December 2017, lending to customers stood at £8.6bn. It has around 1,000 staff.
Oliver said: "I am very excited about joining Aldermore. It’s a bank with a refreshing culture, strong values and an innovative approach to helping homeowners, savers, professional landlords and SMEs.
"They are doing a great job in supporting individual customers and the UK economy. I’m looking forward to helping to raise awareness of a bank committed to providing banking as it should be."
Aldermore currently uses agencies Lansons and Cicero.