With Benfica, he would win five major honours, including back-to-back league titles, and set his single-season scoring record with 27 goals.

Mitroglou was born on 12 March 1988, in Krinides, Kavala, Greece, and emigrated as an infant with his parents from his native country to Germany.

During the final stages of the season, Mitroglou played an important part in helping Olympiacos claim their 36th league title, scoring the last-minute winning goal (2–1) in their match against AEL, this time assisted by Mirnes Šišić.

[13] For the 2008–09 season, Olympiacos appointed Ernesto Valverde as their new head coach, who dropped Mitroglou because he wanted his team to play a quicker and more offensive style of football.

[16] Mitroglou scored the equalizing goal in an eventual 2–1 defeat of Standard Liège in a UEFA Champions League group stage match on 21 October 2009.

[18] Mitroglou scored both goals in a 2–0 win against rivals Panathinaikos after assists by Dudu Cearense and Jaouad Zairi.

Despite being a starter and scoring a spectacular goal in the opening league match against Iraklis (1–2 away loss),[21] Mitroglou only made four more appearances as Valverde chose to use Kevin Mirallas and Marko Pantelić instead.

Mitroglou also scored a goal in the semi-finals of the Greek Cup against Asteras Tripoli, sending his team reach the final against parent club Olympiacos.

Mitroglou showed a good form in the pre-season training scoring a total of three goals, two of them in a friendly against Spanish side Málaga at the Karaiskakis Stadium.

[34] With Djebbour absent due to injury, Mitroglou was a starter for the second group game of the UEFA Champions League against Arsenal in the Emirates Stadium, where he scored the equalizer in an eventual 3–1 loss.

[41] During the pre-season preparation at Seefeld, Mitroglou scored a goal in a 2–1 friendly win against Azerbaijani club Simurq PIK.

[citation needed] He next scored two goals at a home win 5–1 against OFI Crete with two headers after two assists from Joel Campbell.

[citation needed] On 31 January 2014, Mitroglou signed a four-and-a-half-year contract for a transfer fee believed in the region of £12 million with English Premier League club Fulham.

[54] On 22 February, he made his debut for Fulham in a 1–1 draw at West Bromwich Albion, replacing Hugo Rodallega after 61 minutes.

Due to various injuries and fitness problems, Mitroglou played in only two more Premier League matches before the end of the 2013–14 season, starting only one, away against Cardiff City.

[58] Three days later, he scored what proved to be the game winner in a 3–2 win over Atlético Madrid in the UEFA Champions League group stage.

[62] In their first match of the Primeira Liga season against Estoril, he opened the scoring in a 4–0 win at the Estádio da Luz.

[72] On 5 March, Mitroglou scored the only goal in the Lisbon derby at Sporting CP's Estádio José Alvalade, giving Benfica the lead in the league, ahead of their opponents.

[77] Two days after the league title celebrations, Benfica announced Mitroglou had signed a permanent contract with the club set to last until 2020,[76] for a €7 million transfer fee, as disclosed by Football Leaks.

[80] On 31 August 2017, French Ligue 1 club Marseille announced the signing of Mitroglou on a four-year contract for a transfer fee of €15 million to Benfica.

[81][82][83] On 28 September, Mitroglou made his competitive debut for Marseille in a 2017–18 UEFA Europa League group stage 1–0 away loss against Red Bull Salzburg, coming on as a substitute in the 79th minute for Maxime Lopez.

[84] On 6 February 2018, Mitroglou scored his first hat-trick for Marseille—to go along with one assist,—in a 9–0 blowout win over Bourg-en-Bresse in the Coupe de France.

[88] On 21 February, he scored his first goal with the new team in the Super League against his former club Olympiacos at the Karaiskakis Stadium, in a match ended 1–1.

[89] In January 2023, Mitroglou signed with German club SpVgg Rheurdt-Schaephuysen in amateur league Kreisliga A Moers.

He participated at the 2007 UEFA European Under-19 Championship, in which he scored the only goal against Portugal at Linzer Stadion in the group stage,[94] as well as in a 1–1 draw against Austria at the Waldstadion.

[98] On 11 September 2012, he scored a goal in a 2014 FIFA World Cup qualifying match against Lithuania, which ended in a 2–0 victory.

[100] Mitroglou scored the only goal in a victory over Liechtenstein, after an assist from Vasilis Torosidis, in their penultimate World Cup qualifying match on 6 September 2013.

[101] He scored two goals on 15 November in Greece's 3–1 home win against Romania in the first leg of their 2014 FIFA World Cup qualifying play-off.

[102] Four days later, he scored the opening goal of the return leg in Romania, which ended in a 1–1 draw and sent Greece to the World Cup final stages in Brazil with a 4–2 aggregate victory.