The Under-23s trio have all been rewarded having impressed in Carlos Corberan's PDL title-winning campaign last season.
Youngsters Stuart McKinstry and Charlie Cresswell have also put pen to paper on their first professional contracts at the club.
Hosannah joined United's ranks from Crystal Palace in 2017 but has seen his appearances limited after picking up a succession of injuries.
Struijk made the move to West Yorkshire from Dutch outfit Ajax in the same year while La Liga giants Barcelona allowed Kun Temenuzhkov to link up with Leeds.
McKinstry joined United initially on scholar terms from Scottish Premiership team Motherwell but has now put pen to paper on a three-year contract.
Highly-rated centre-back Cresswell - the son of former United striker Richard - has also signed similar terms with Leeds hoping they can emulate two other recent Thorp Arch graduates.
A club spokesperson said: "The duo will now be looking to follow in the footsteps of Kalvin Phillips and Jamie Shackleton, who have both gone on to progress to regular first team football."