Calderón, 26, has spent the majority of his professional career with Liga de Quito in the Ecuadorian first division, winning three league championships as well as the prestigious Copa Libertadores.
Calderón will be eligible pending receipt of his P-1 work visa and International Transfer Certificate. Per league and team policy, terms of the deal were not disclosed.
"Diego is a versatile, talented defender who will come in and compete for a spot in our back line," said Rapids Technical Director Paul Bravo.
"He can play in the middle or on the left, and has extensive experience, having won league and continental titles and been a part of his national team throughout World Cup qualifying. We're excited to bring him into the group."
Calderón joined Liga de Quito in 2003 and made his first team debut in the top division in Ecuador in 2005 at just 18 years old as the club won the 2005 Apertura championship.
He spent a season in 2006 on loan Deportivo Azogues, making 11 appearances and helping the team gain promotion to the Ecuador Serie A.