He was born in Vitoria and joined the Franciscan order, becoming ordained in 1752. In 1758 he volunteered to work in America. He arrived in Mexico in 1761 and was sent to Baja California in 1768. Following the establishment of the mission at San Diego in 1769, he went to Northern California in 1773. He was never happy in California. He based himself in San Diego and remained there until 1775, he helped establish the mission at San Juan Capistrano before the murder of Father Luis Jayme and Kumeyaay Indian unrest caused his return to San Diego and the general withdrawal of Spanish operations. In late 1776 he went to San Luis Obispo before again returning to San Diego in 1777 when he was made minister there. He was made the second Presidente of the missions in California in 1785, replacing Junipero Serra, and transferred to the Carmel Mission. On his death he was succeeded by Estevan Tapis.
He personally established nine of the twenty-one "Alta California" missions:
Father Fermin Francisco de Lasuen was born on June 7, 1736 at Vitoria in Cantabria, Spain.
In the summer and fall of 1776, the missions were re-opened and Father Lasuen went with Father Serra to San Luis Obispo, where he stayed until 1777 when he was appointed minister of Mission San Diego.
Lasuen never adjusted well to life in California and he repeated asked for retirement or transfer, stating that only obedience kept him here.