The 27-year-old has been capped 11 times by Ecuador, scoring one goal, while he has tallied 10 goals in 30 appearances for El Nacional since joining the club in 2009.
"We have been scouting a number of players for a long time ahead of this decision and I believe Edmundo has the potential to help our club right away," said Earthquakes general manager John Doyle. "We have been looking for attacking players that can score goals and provide a presence in the box. Edmundo is a well-rounded forward who can play with his back to the goal and get behind defenses. We are excited to bring him in as the team makes its push to qualify for the postseason."