Ciss was born in Dakar, and joined the Diambars FC academy at the age of 12, joining his older brother Saliou and father Ibou, who was a coach there.[1] He started his senior career at Diambars, before joining LigaPro side C.F. União on 31 July 2017.[2]
Ciss made his professional debut on 13 August 2017, coming on as a late substitute for Gonçalo Abreu in a 2–0 home win against Real S.C. He scored his first goal abroad on 29 October, netting the game's only in a home defeat of U.D. Oliveirense.
On 30 August 2018, after União suffered relegation, Ciss moved to F.C. Famalicão on a one-year loan deal, still in the second division.[3] He contributed with four goals during the campaign, as his side returned to Primeira Liga after 25 years.
On 2 September 2019, Ciss was loaned to Spanish Segunda División side CF Fuenlabrada, for one year.[4] The following 13 July, he signed a permanent contract until 2023 with the club.[5]