Mr Paisley, 87, now known as Lord Bannside, led the DUP into power-sharing at Stormont with Sinn Fein in 2007.
He was admitted for tests to the Ulster Hospital near Belfast in December and spent just over two weeks undergoing treatment.
His son Ian Paisley Jnr said: "I am delighted he is back home again and settled. I am very grateful for the wonderful work of the hospital staff."
In February 2012, the former North Antrim MP suffered from heart failure but returned to public life after recovering.
The previous year he had a pacemaker fitted at St Thomas' hospital in London after falling ill at Westminster. Paramedics had to revive him following his collapse in parliament.
Mr Paisley stood down as Northern Ireland's first minister in 2008 and ended 60 years of full-time ministry in January 2012.
The veteran unionist and fundamentalist Protestant preacher has been a colossus of Northern Ireland politics.
Mr Paisley established the DUP in 1971 and opposed every attempt by successive British and Irish governments to create a power-sharing government. But a dramatic change of heart came in 2006.