Career
Alonso scored a goal in the CONCACAF Champions" Cup 2008 quarter-final match against Atlante F.C. on March 19, 2008. Alonso made his debut in the Costa Rican Premier Division on 20 February 2002 for Deportivo Saprissa against Santos de Guápiles. He then spent two years on loan at Cartaginés and joined Alajuelense in 2012 after being released along with Esteban Sirias by Saprissa in December 2011.
He played in the 2001 Fédération internationale de football association U-17 World Championship finals in Trinidad and Tobago.
Alonso made his senior debut for Costa Rica in a March 2008 friendly match against Peru and has earned a total of 21 caps, scoring 3 goals. His final international was a September 2010 friendly against Jamaica.