After three efficient years he joined Olympiacos from Atromitos on 19 August 2011 but he remained in his former club on a one-year loan.
At the end of the 2011/12 season, besides the fact that it was amongst the priorities of the Olympiakos' former coach Leonardo Jardim, due to the numerous quality midfielders in the club and the fact that it was difficult for him to play on a regular basis, Olympiakos decided to give him to Aris for the rest of the season 2012/13.
Unfortunately, Tatos with his miraculous left foot and unexpected inspirations can not progress in a football season that even players with his own skills are rare in Greek courts.
The transfer was completed at the offices of Olympiakos and immediately after Tatos said the following: "I am very happy to be back in the team that helped me improved as professional in my early football years.
I will promise to give 100% to help Atromitos to achieve its goals and specifically in the preliminary round of Europa League.
[8] On 5 January 2019, Andreas Tatos appealed against Elazığspor due to the financial inconsistency, stayed free and signed for a year-and-a-half in Altay for an undisclosed fee, continuing his career in Turkey's second division.
[10] On 5 August 2011, Tatos was one of the three new faces called by Fernando Santos on the Greece national football team for the friendly match against Bosnia and Herzegovina, however he wasn't used.