Before returning to Mexico, Tritschler was invited by Manuel Fulcheri y Pietrasanta, on the recommendation of Louis Billot, to serve in the Archdiocese of Mexico. However, fears of conscience delayed his ordination. His fears were relieved when Bishop José Ramón Ibarra y González, the Bishop of Puebla de los Ángeles, granted his request that he be ordained by his brother Bishop Martín Tritschler y Córdova, Bishop of Yucatán. On 8 May 1903, on the Feast of the Apparition of St. Michael, he received from his brother the tonsure and minor orders. On 5 June 1904, in the Church of San Francisco El Grande, he received the subdiaconate from Bishop Francisco Orozco y Jiménez, Bishop of Chiapas. On 13 June 1904 in the Church of San Antonio de Padua, his brother Martín ordained him a deacon, and he was ordained to the priesthood on the morning of 19 June 1904 in the chapel of the Archbishop's palace of Puebla. He celebrated his first Mass two days later on 21 June 1904, the Feast of St. Aloysius Gonzaga, in the Church of Nuestra Señora de Ocotlán, near the city of Tlaxcala.