Having received a deadline day call from Mike Phelan, he felt the time was right to make a move and try and gain regular first team football, signing a three-year deal at the KCOM Stadium.
“It's an important time in my career and I think every player of my age wants to try and start playing regular first team football," said Weir to the Tigers website.
“I couldn't be happier to join Hull and really get my career started. The key thing for me is that I can be a regular part of the first team squad here and I hope I can help as the club continues to move forward.
“I'm just looking forward to cracking on now and getting started here. It will be an exciting time once the international break is over and I can't wait to meet the rest of the lads."
“I've played with 'Keano' a few times and he's a great player," added Weir.
“I'm looking forward to linking up with him again."