Panathinaikos Donis is a product of
Panathinaikos' youth ranks. He promoted to the first team on July 1, 2012, signing a contract which keeps him in Panathinaikos until 2015. He made his debut at the 4–0 win against
Proodeftiki for the
Greek Cup. He made his championship debut at a game against
Levadiakos on 18 December 2013, scoring his first goal with the team. On 15 February 2016,
Panathinaikos officially announced the loan of Christos Donis to Swiss club
Lugano until the end of the season, with a contract option to purchase him. The 21-year-old midfielder wοuld have his younger brother, Tasos (who joined
Zdeněk Zeman’s team on loan from
Juventus), as a teammate. On 27 June 2016, after an unsuccessful semester with
Lugano, his club officially announced his loan to the
Super League club
PAS Giannina until the end of the
2016–17 season. On 29 November 2016, he scored the only goal in a 1–0 away
Greek Cup win against
Agrotikos Asteras, helping his club to proceed to the last 16. In January 2017 he was transferred to Iraklis, on loan. On 5 April 2017, he was the only scorer in a crucial 1–0 home win game against
Levadiakos, sealing a crucial victory in his club effort to avoid relegation. On 9 April 2017, he scored for a consecutive game sealing a valuable 2–1 away win against his former club
PAS Giannina in his club's constant effort to avoid relegation. On 30 April 2017, he helped his club to sealing a 2–2 away draw against
Asteras Tripolis, with a wonderful
free kick, concluded his exceptional performance in the second half of the
2016–17 season. Donis returned to
Panathinaikos for the
2017–18 season. On 21 January 2018, he opened the score in a hammering 4–0 home win game against
Kerkyra. It was his first goal with the club after almost four years. On 6 April 2019, he scored his first goal for the
2018–19 season was in the right place at the right time to convert an excellent pass from Italian striker
Federico Macheda, as Panathinaikos moved to within five points of fifth-placed
Aris after claiming a solid 2–0 home win over the Thessaloniki club at the
Olympic Stadium. On 12 January 2020, he scored his first goal for the
2019–20 season as he intercepted the ball from a poor clearance made by Panionios defence, and he surged forward before hitting a powerful diagonal shot past the goalkeeper,
Jérémy Malherbe to open the score in a 3–0 home win game against
Panionios.
Ascoli On 16 September 2020, he signed a three years' contract with Italian
Serie B club
Ascoli, on a free transfer with annual fees at the range of €300,000. On 12 February 2022, Donis' contract with Ascoli was terminated by mutual consent.
VVV-Venlo On 19 January 2021, he was loaned to VVV-Venlo, where he reunited with his brother
Tasos.
Radomiak On 24 January 2023, after spending most of the winter training with Polish
Ekstraklasa side
Radomiak Radom, Donis signed with them until the end of the season, with a two-year extension option. ==Personal life==