The 26 year old left sided player is a close friend of Latics star Maynor Figueroa and will join when his contract with Sporting Kansas City expires at the end of the month.
The Latics obtained international clearance to sign Espinoza this morning and Roberto Martinez was pleased with his new addition.
He said: “We prepared an excellent case for Roger and it is great news for us that he can now join up in January. “He is a player we have been following closely since 16th of June 2010, when he made his debut in the World Cup versus Chile. “In that game, he showed tremendous potential and slowly, he has been developing into an exciting footballer over the last three seasons in the MLS and has enjoyed terrific experiences at international level, specifically his role with Honduras in the Olympic games. “The games versus Spain and Brazil in that tournament showed the winning and strong mentality that he possesses which will be an important asset to our squad.”