He made his first team debut on 21 January 2014, coming on as a second-half substitute for Thiaguinho in a 1–0 Campeonato Carioca home win over Madureira.

Willian Maranhão subsequently became a regular starter for the side, and scored his first senior goal on 13 September 2017, netting his team's third in a 3–1 home success against Tigres do Brasil, for the year's Copa Rio.

[3] On 5 September 2018, Willian Maranhão was presented at Série A side Vasco da Gama,[4] on loan until the end of the year.

On 25 March 2022, Bahia announced the transfer of Willian Maranhão to Santos, who paid a R$ 500,000 fee for 70% of the player's economic rights.

[12] Willian Maranhão made his debut for Peixe on 5 April 2022, starting in a 0–1 Copa Sudamericana away loss against Banfield.