The deal, which comes with a transfer option, involved Vancouver sending allocation money to Toronto FC, which had first right of refusal to Techera.
"We are thrilled to welcome Cristian to our club," Vancouver coach Carl Robinson said in a statement. "He is a quick natural winger, who can play on both sides of the pitch. He has great technical ability and will excite in the attacking third."
The five-foot-two, 150-pounder had 10 goals in 24 games for River Plate Montevideo this season.
He made his debut with the club in April 2010 at the age of 17. In six seasons in Uruguay's top league, Techera started 45 of his 74 appearances and scored 18 goals.
During the last three seasons at River Plate, Techera played with striker Leandro Rodriguez, the younger brother of Whitecaps centre back Diego Rodríguez. Techera was also teammates with Vancouver midfielder Nicolas Mezquida on the regional team of Paysandu
Striker Octavio Rivero, a young designated player, is the fourth Uruguayan on the Whitecaps roster.