The Tigers have an option to increase that deal by a further year if Alzate impresses.
Colombia international Alzate, who is now 26, was with Ipswich last month after his Brighton contract ended in the summer.
“I’m extremely delighted to be here and for it to finally get done. Speaking to the directors, the ambition of the club was why I decided to join,” he told the Tigers official website.
“Ex-teammates of mine have played here – Noah Ohio and Aaron Connolly – and said good things. I know Ryan Longman and Carl Rushworth from Brighton and Gustavo Puerta from the national team.
“I’ve never played here and I can’t wait to get on the pitch. I’m looking forward to getting my first minutes, playing, getting some wins and hopefully contributing some goals and assists.
“Individually, I want to get as many games in as I can, get my stats up with goals and assists and, with my experience, help the team have a good season.”