Born in Salgueiro, Pernambuco, Santos joined Salgueiro Atlético Clube's youth setup in 2005 after starting out at Escolinha de Futebol do Tête.[2] He made his debut for the former in 2008, appearing rarely in the Série C.
On 11 July 2012, Santos signed a two-year contract with S.C. Braga, initially being assigned to the reserves also in the second tier.[5] After being an ever-present figure for the latter, he made his first-team – and Primeira Liga – debut on 9 March of the following year, playing the full 90 minutes of a 2–0 home win over C.S. Marítimo.[6]
Santos scored his first goal in the Portuguese top flight on 3 May 2013, his team's second in the 3–2 victory at Moreirense FC.[7] On 25 September he signed a new five-year deal with a €20 million clause,[8] after the Minho side refused an offer from Stade Rennais FC.[9]
Santos was an undisputed starter the following two campaigns, attracting interest from a number of teams, one of them being AS Monaco FC.[10]
On 27 August 2015, Santos agreed to a five-year deal with Valencia CF for a fee of €9.5m.[11][12][13] His maiden appearance in La Liga occurred on 22 September, as he featured the entire 1–0 away loss against RCD Espanyol.[14]
On 24 January 2019, Santos joined Al Ahli Saudi FC.[17] On 13 August, he made a return to Portugal on a season-long loan to Rio Ave FC,[18] signing a permanent contract with the latter club the following May.[19]
^"Aderlan Santos está confirmado" [Aderlan Santos is confirmed]. Record (in Portuguese). 11 July 2012. Archived from the original on 15 September 2014. Retrieved 15 September 2014.
^Marques, Sara (3 May 2013). "Moreirense-Sp. Braga, 2–3 (crónica)" [Moreirense-Sp. Braga, 2–3 (report)] (in Portuguese). Mais Futebol. Retrieved 27 August 2015.