The Russian-born Dutch 23-year-old joins from Sparta Rotterdam where he spent three seasons.
Manager Jackie McNamara was pleased to announce the news and told his club's official website, "I am extremely happy to bring Mario to the club.
"He will bring a different dimension to our attack. He is strong, tall and quick and is at the right age to progress his career.
"Mario knows the players are developing here and wants to be part of that.
"We want the club to grow continually and with this signing we have enhanced our squad and improved our striking options."
Bilate, who is relishing the chance to play in Scotland, said, "This is a wonderful opportunity for me. United play attractive attacking football and the club will help me improve as a footballer.
"I am looking forward to showing what I can do. Scottish football will suit me and I want to play a big part in moving the club forward."
Bilate joins new defensive recruits Jaroslaw Fojut and Callum Morris, while McNamara's squad has been further boosted by the recruitment of Scottish youngsters Charlie Telfer and Blair Spittal.
The Tannadice club, however, sold attacking Ryan Gauld to Sporting Lisbon for a reported £3million and lost stopper Gavin Gunning to Birmingham after his contract ran out.