Blackburn have signed Liverpool left-back Sam Hart, while MK Dons defender Paul Downing and West Brom midfielder Rekeem Harper have joined on loan.
Ex-Port Vale loanee Hart, 20, has joined the League One side for an undisclosed fee on a two-year contract.
Harper, 17, made his Premier League debut earlier this month, becoming only the second player born this century to feature in the top flight.
He signed his first professional deal before completing his season-long move.
Former Walsall centre-back Downing, 25, will also stay at Ewood Park until the end of the 2017-18 campaign, having made 46 appearances for the Dons since joining them last summer.
Find all the latest football transfers on our dedicated page.