Slaftsakis played youth basketball with Halkidona and Mantoulidis, before he started his pro career.

Slaftsakis began his professional career with the Greek League club KAOD,[2] during the 2012–13 season.

He left KAOD, when the club was relegated down from the first-tier Greek Basket League, due to financial problems, in 2015.

On July 29, 2018, he joined Aris of the Greek Basket League, where he spent three consecutive seasons.

In 28 league games, he averaged 2.3 points and 1.4 rebounds in 8 minutes per contest.