The 50-year-old Kear, who has been out of work since being sacked by Hull in April, has been appointed as short-term successor to Tony Smith, who left the relegation-threaten Wildcats a week ago.
Kear has been put in charge until the end of the season and has six matches to help Trinity avoid the drop into National League One.
Their 42-20 home defeat by Bradford on Friday left them bottom of the table, two points adrift of Wigan, after winning just six of their first 22 games.
Kear was due to take up his position today and his first match will be against another former club in Castleford at the Jungle on August 5.
The former Sheffield Eagles boss, who famously guided the South Yorkshire club to victory over the Warriors in the 1998 Challenge Cup final, was the first to throw his hat into the ring for the vacancy but it appears he was not the first choice.
Former St Helens and Wigan coach Ian Millward claimed he rejected an offer and Salford assistant James Lowes is also thought to have turned down the chance to become a head coach.
Others linked with the job were Kear's former right-hand man at Hull Richard Agar and York coach Mick Cook.
Kear, who hopes to appoint an assistant early this week, is relishing the opportunity to return to the game.
"It's nice to be back involved," he said. "It's a massive challenge but one I'm looking forward to.
"I am happy to come here and work very hard for two months. I've missed the daily slog."
Two of Trinity's last six matches are derbies with Kear's old club and the irony is not lost on the Castleford-born former winger.
"It's a great first match for me personally," he said. "I always look forward to coaching against Castleford.
"There is a certain irony in that the first game of my tenure and the last game of the season are both against Castleford. I do know a fair bit about Castleford because I watch them.
"I have a soft spot for them but you've got to put all sentiment aside. I have to do a job which is to keep Wakefield in Super League. I am confident in my own ability and I am willing to back myself."