The 24-year-old could partner Eric Brunner as Portland's starting center back duo in 2012.
Mosquera, 24, joins from Club Deportivo La Equidad Seguros of the Colombian first division, where he played in 34 matches and scored two goals during the 2011 season.
“Hanyer is a player we’ve had our eye on for 18 months,” said Timber general manager Gavin Wilkinson. “He has all the attributes needed to become one of the top defenders in MLS.”
The six-foot-one defender has played the last four seasons in Colombia’s top flight, the Liga Postobón, with Corporación Deportes Quindío (2008-10) and La Equidad (2010-11). In total, Mosquera appeared in 127 matches and scored six goals during his career in the Liga Postobón.