On 19 March 2007, Paul Hart was appointed Director of Youth Operations at Portsmouth. He was asked to take over as caretaker manager, initially for one game only, following the sacking of Tony Adams on 9 February 2009.
Shortly afterwards, Hart brought Brian Kidd in as his assistant. He won his first game in charge 2–0 at home to Manchester City on 14 February 2009.
Hart continued as caretaker manager until the end of the 2008–09 season, Portsmouth executive chairman Peter Storrie announcing in March 2009, after a close 1–0 defeat to Chelsea, "(Alexandre Gaydamak) and I have been delighted with how the team have fared. They both have so much experience in the game and they have the respect of the players. We will review the managerial situation again at the end of the season."
However,Portsmouth, a club in turmoil and on the brink of administration, had the worst ever start by a Premier League team, losing their first seven league games. This run was finally ended on 3 October when Portsmouth recorded a 1–0 win against Wolverhampton Wanderers at Molineux.
On 24 November, with only two Premier League wins in 13 games and three points adrift at the bottom of the table, Hart was sacked. He declined the offer of an alternative role as technical director responsible for players aged 18–21, and left the club.