In 1624 Pereira was admitted as chaplain-singer at the Ducal Palace of Vila Viçosa, the ancestral seat of the Dukes of Braganza, the most important title in the peerage of Portugal in the middle of the 17th century.
[2] In 1629 Pereira replaced Robert Turner (c. 1578-1629) as mestre de capela.
[3]: 162 After the overthrow of the Philippine Dynasty on 1 December 1640, which had ruled Portugal since 1580, João, Duke of Braganza became king and the ducal chapel moved from Vila Viçosa to Lisbon.
In 1641, after the retirement of Filipe de Magalhães, Marcos Soares Pereira was appointed mestre da Capela Real, a position he held until his death in 1655.
Nevertheless, the library catalog partially survived and there we can find the entry for fifty-eight of Pereira’s compositions, fifty-four vilancicos and four psalms, Confitebor, Beatus Vir, Laudate Pueri and Laudate Dominum.