Spanish monarchs ruled a global empire encompassing millions of colonial subjects for nearly three hundred years. One key factor in the longevity of the Spanish Empire was its skillful integration of elements from an even longer-lasting, centralized Institution--the Catholic Church. Through a focus on San Felipe de Jesús, a Mexico City-born saint, this dissertation analyzes the pious imperialism of the Spanish Empire in the Catholic missions of Japan, the politics of beatification in Rome and local devotions in Mexico City. Funded by Philip II, Spanish missionaries spread across the Atlantic and then to the Pacific. The mission of Spanish Franciscans in Japan including San Felipe exemplified the orthodox and expansionistic tendencies of this movement. The friars’ uncompromising zeal caused them to reject Japanese society and authority, something which led to their executions in 1597. Spanish subjects thrilled to the martyrs’ inspiring story and supported their beatification cause. The Spanish king, too, actively promoted new holy figures in Rome for political and pious reasons. During the seventeenth century, more than half of the new beatified or canonized holy figures came from the Spanish Empire, including the Nagasaki martyrs. As each new saint earned a feast in liturgy, worship in Spanish territories began to disseminate not only Catholic values, but also divine favor toward the Spanish Empire and its monarch. The liturgical schedule of colonial Mexico City shows that Spanish Catholicism projected both Church and Empire across the Atlantic. As the Catholic Church had found, cults to saints formed effective imperial ties because they could also attract and adapt. Civic and religious leaders in Mexico City molded the cult to San Felipe to express municipal pride, to assert the city’s place in the Spanish Empire and to commemorate its contributions to Catholicism. Devotions to saints, then, captured the potentially-divisive power of identity to reinforce Empire and Church. Pious imperialism worked well until Bourbon-era reforms distanced the Spanish monarch from the devotional culture in Mexico City and interrupted the mediating power of saints’ cults. The Spanish Empire was less able to withstand shocks like the political instability of the early nineteenth century. / text