After his uncle died in a shipwreck, Duarte de Lemos succeeded him as captain-major of the Sea and Coast of Ethiopia and Arabia, that is, the western part of the Portuguese Empire in the Indian Ocean.

[1] Under pressure from the latter, Lemos returned to Portugal, having left in Portuguese India a solid reputation as "the most efficient tax collector that King Manuel I has ever sent to the East".

Between 1518 and 1520, he was involved in a conflict with the Abbess of Lorvão Abbey, over a donation he had received from the Count of Faro and of Odemira (a close relative of the King), who was also Lord of Aveiro.

Duarte de Lemos entered a mangrove swamp and then built on a hill his personal residence and the chapel of Santa Luzia, now considered to be the oldest building of the present-day city of Vitória.

[13] In 1549, he was back in Lisbon, where - on 1 August 1549 - he received confirmation of the donation of the island of Santo Antônio from King João III.

From there he wrote to the King of Portugal, on 14 April 1550, reporting that in the land of Porto Seguro "there was gold" and stating that he was willing to organize an expedition to find it, for which he requested support from the Crown, adding that the local (Amerindian) tribes "were at peace" and "very friendly to us".