Marcin Mozejewski was born in 1827 in the village of Filipowo, Suwalki (Russian-held Poland). After having studied in the local schools of Suwalki, he entered the seminary at Plock (where he was ordained in 1853). Before embarking on a career of missionary work that included traveling to Brazil and Argentina in South America, Mozejewski served at vicar in parishes in his native land.

Having then come to the United States, he ministered in many Polish parishes throughout the country. While in Ilinois, he served churches in Le Mont and Chicago; in Buffalo, he became the second pastor of St. Adalbert Parish.

When he arrived in Buffalo, Mozejewski discovered that the structure of St. Adalbert Church had burned to the ground several weeks earlier. He consequently set about planning the new and magnificent basilica-like structure which stands to this day. Mozejewski stayed in Buffalo less than a year before switching pastorates with Ks. Antoni Lex of St. Josaphat Parish in Detroit, MI. (It was Lex who was responsible for completing the building of the new St. Adalbert Church.)

After Detroit, Mozejewski traveled to Wisconsin where he worked in the town of Berlin until 1896. He was then made pastor of the Polish parish in Chestochova, TX. In 1898, he was assigned to the small parish of Sacred Heart of Jesus in Two Rivers, WI where he remained until his death on September 23, 1899 at age 72. (The history of the Polish settlements which Mozejewski began writing in 1888 was never completed before his death. Rev. Waclaw Kruszka would publish the first such a compilation some twenty years later.

This silver-bearded missionary, the author some ten pamphlets and books on religious topics, was also well respected and known as a golden-tongued speaker. When the Polish seminary was in need of faculty members, he found his way there and served where he could. His name was suggested as a possible candidate for bishop by his fellow Polish clergymen during their 1891 convention.