The Tigers boost their ranks as former Leeds defender joins the Championship side on a two-year deal after a period training with the club
The 27 year old had been training with the Championship side for the past three weeks and moves to the KC Stadium as a free agent after ending a two year stay at Elland Road.
Hull boss Steve Bruce, who happens to be Alex's father, says he has no qualms over handing his son a contract at the club, insisting that the 27-year-old is an accomplished player.
"When you look at what's going around on the Bosman market, he makes a very good free transfer," Bruce senior told hullcityafc.net.
He continued: "He's 27 and he'll handle this division. He's at the peak of his career and looks in good shape. I'm sure he'll be a decent acquisition.
"Defensively, in terms of numbers, we're a bit thin with the injury to Liam Rosenior and Jack Hobbs out until Christmas.
"It's imperative that you have cover in the right areas and Alex can fill in anywhere along the back line," added the former Sunderland boss.
Alex Bruce has made two senior Republic of Ireland caps to his name after declaring for the Boys in Green through his Irish grandmother.
However, it emerged that the defender was pondering a switch of association to the Irish Football Association in June 2011, with then manager Nigel Worthington saying he had spoken with him.