Striker Bent, who scored 12 goals in 17 appearances on loan at the Championship club last term, was released by Aston Villa after his contract expired on Monday and has signed a two-year deal at a Midlands rival.
Pearce’s contract at Reading was allowed to expire this month too and he has signed a three-year deal at the Rams.
Bent, 31, had a troubled time at Villa, making just eight appearances over the last two years, and also spent time on loan at Fulham last season and Brighton at the end of 2014 before joining Derby in January.
They just missed out on the play-offs under Steve McClaren and subsequently replaced the former England boss with former Real Madrid and Paris Saint-Germain assistant Paul Clement.
Bent began his career at Ipswich before establishing himself as a consistent goalscorer at Charlton. Big-money moves to Tottenham and Sunderland followed before Villa paid £18m for him in January 2011.
Pearce meanwhile, a 26-year-old central defender, is a Republic of Ireland interntional who has been at Reading since 2006 and played in the Premier League amongst 200 appearances for the club.
He previously spent time on loan at Northampton, Norwich, Bournemouth and Southampton early in his career before establishing himself as the Royals’ first-choice defender, making 49 appearances last season.