The former Manchester City assistant manager, replaces Dave Sarachan, who was fired on June 20. Longtime Fire assistant Dennis Hamlett coached the team on an interim basis for the last three games -- two ties and a loss.
Osorio, 46, was with Man. City from 2001-2006 and spent the last year at Millonarios in his native Colombia. He previously spent two seasons (2000-01) as an assistant coach with MLS's MetroStars.
Fire president John Guppy was an executive at the MetroStars when Osorio worked at the club.
Osorio is a graduate of Southern Connecticut State University, where he received a B.A. in exercise science. Much of his soccer work has been in the area of fitness training. Injuries have been a problem this season for the Fire.