Born in Tripoli, Tasoulis began his football career with local side Asteras Tripolis, youth teams. In the summer of 2010 he transferred to Athinaikos, where he played for one season.
He moved to Fostiras in 2011. In his first year in Fostiras, he contributed the club's championship in the 8th Group in Delta Ethniki,[1] which led to the renewal of his contract for another year. Continuing his excellent performances with the club in Gamma Ethniki, signed a new two-year contract as a personal choice of the coach of the club Jacky Mathijssen.[2] During the 2013–14, season he made the best year with the club, while scoring the winning goal in the delays of the last game that led the club to the playoffs for the rise in the Super League Greece.[3][4][5]
In 2014, Panionios announced the agreement with Tasoulis for three years.[6] On 25 August 2014, he made his debut with the club, playing for first time in the Super League Greece in a 2–1 home win against Ergotelis. His remarkable season, except his first call in the Greece national team was the cause that the left-back is very high in the transcriptional list of many clubs including AEK Athens.[7] On 11 December 2016, he scored his first goal with the club, in a 1–0 home win against Kerkyra.[8]
On 7 July 2017, French Ligue 2 club RC Lens signed Tasoulis on a season-long loan contract from Panionios, and they intend to put a purchase option on the contract. The French club was among the favourites after a struggling season in order to be promoted to Ligue 1.[9] Panionios earned €200,000 as a rent fee for the 26-year-old defensive, and the market clause set for next summer is expected to be around €300,000. Before signing with Lens, he extended his Panionios contract which would have expired in 2018 until 2019, since otherwise the Greek left-back would be free to negotiate the next step in his career as his own.[10]
On 8 January 2018, Tasoulis returned to Panionios after lacking playing time at Lens.[11]
On 20 June 2018, Asteras Tripolis officially announced the signing of the Greek defensive on a two years' contract for an undisclosed fee.[12] On 20 July 2020, he signed a new contract, running until the summer of 2021.[13]