After starting out at Casa Pia, he went on to amass Primeira Liga totals of 118 matches with 22 goals at the service of Vitória de Setúbal, Rio Ave and Braga.

In the summer of 2012, Santos joined Vitória de Setúbal, making his debut in the Primeira Liga on 19 August of that year by coming as a 68th-minute substitute in a 2–2 away draw against C.D.

[12] After returning to his parent club, Santos helped to consecutive fourth-place finishes and scored a total of 12 goals in the process.

[13][14] On 22 May 2016, he replaced Josué for the last minutes of regulation time in the national cup final (2–2 draw), and converted his penalty shootout attempt in a 4–2 victory at the Estádio Nacional.

[16][17] He made his Major League Soccer debut 12 days later, playing 28 minutes in a 1–1 away draw against Orlando City SC.

"[23] During the 2019 season, Santos recorded best professional figures of 11 goals from 33 games,[24] while playing both as a winger and stepping in as an attacking midfielder for the injured playmaker Federico Higuaín, who had suffered an anterior cruciate ligament injury.

[27] Santos moved back to winger for the 2020 season, and scored eight goals and assisted on seven more in 26 matches across all competitions as his team won the MLS Cup for the first time since 2008, making him the first Portuguese player to earn a medal in the tournament; he missed the final against the Seattle Sounders due to a positive COVID-19 diagnosis, however.

[29] On 8 April 2021, Santos converted a penalty in a 4–0 victory over Real Estelí FC in the round of 16 of the CONCACAF Champions League,[30] but injuries to incumbent left-back Milton Valenzuela forced him to cover that position for the majority of the campaign.

[34] Following the return of Valenzuela, Santos was pushed higher up the pitch, resulting in a one-goal, two-assist performance in a 4–0 victory against Inter Miami CF on 16 October.