Oikonomou with AEK Athens in August 2018
|Date of birth||6 October 1992|
|Place of birth||Ioannina, Greece|
|Height||1.89 m (6 ft 2 1⁄2 in)|
|AEK Athens (on loan from Bologna)|
|2017–2018||→ SPAL (loan)||4||(0)|
|2018||→ Bari (loan)||3||(0)|
|2018–||→ AEK Athens (loan)||6||(0)|
* Senior club appearances and goals counted for the domestic league only and correct as of 23:16, 8 December 2018 (UTC)|
‡ National team caps and goals correct as of 11 September 2018
Born in Ioannina, Oikonómou began playing football with PAS Giannina. On 14 November 2012, he made his debut for the Greece U21 in a friendly match against Austria U21. He played only one season with the club having 23 appearances in all competitions.
After a strong 2012–13 season with PAS Giannina, Oikonomou signed a contract with Cagliari, a team in Serie A, the top league in Italy. He was the first ever player in the history of PAS Giannina who managed to sign directly a contract with a foreign club. His former club will receive an amount that will reach €500,000,  On 6 April 2014, he made his debut with the club in a home loss against Roma.
On 1 July 2014, the Greek defender signed a contract with Bologna in Serie B on a transfer deal which involved striker Alessandro Capello, who moved permanently from Bologna to Cagliari. Oikonomou had made very few appearances for Cagliari during the previous season, thus he changed his football environment. On 23 September 2014 he made his debut with the club scoring in a 1–0 away win against Ternana Calcio. His remarkable season attracted the attention of several other Italian clubs, such as Lazio and Hellas Verona.
Despite his initial strong performances on the pitch, in March 2015, Marios Oikonomou went through a difficult spell in which he was forced to stay in the bench after the arrival of Daniele Gastaldello. The transition to the three-man defence allowed him to return to the field and to unlock the game against Livorno by scoring a goal giving three key points in the race for promotion. He insisted on the method of training and the managerial abilities of Luis Diego López. Oikonomou is necessary to turn into a game the good things done in training: "We must think only of what we feel in the week and put it into practice in the match. There is nothing to change in our daily work even though we do few goals." But even with the arrival of Gastaldello, Oikonomou has seen it as a stimulus: "I tried to look on the bright side - admitted the defender - from players like him and Domenico Maietta I can learn a lot, they both have a valuable experience. With them I feel good, and now with the three-man defence we can do good things ".
On 20 September 2015, he helped his club to claim their first win since gaining promotion back to Serie A by beating Frosinone 1–0 at the Stadio Renato Dall'Ara. Bologna took the lead in the 27th minute as Anthony Mounier was picked out by Marios Oikonomou's ball over the top, before lashing a fierce drive across the keeper and into the far corner. Three days later, Oikonomou impressed enough against Fiorentina to have him turn to substitute, but eventually Bologna were undone and lost 2–0. The Greek defender linked up well with Rossettini to keep out the Viola for over an hour but eventually the home side’s pressure told. He won tackles, won headers and made clearances throughout as Fiorentina threatened to run riot. Will be disappointed to be on the losing side and was unfortunate to be so.
Playing for Bologna since 2014–15 season, the Greek centre-back Marios Oikonomou had his own deal with Felsinei and officially extended his contract until June 2020. On 27 October 2015, Oikonomou will be out of action for three to four weeks with a thigh strain. The centre-back pulled out during the warm-up for last night’s 1–0 defeat for Serie A to Inter and had been due to start the match. He underwent tests and they highlighted a Grade I lesion to the left femoral bicep. The recovery time is expected to be around three to four weeks, confirmed the club medical staff. On 6 December 2015, he returned to the starting XI in the 15th day of the Serie A campgain, in a 3–2 home win against Napoli. On 3 February 2016, in an away game against Frosinone, he was sent off for receiving two yellow cards, one for a somewhat harsh handball decision. He started the 2016–17 season as a starter. He finished the season having 22 appearances in both Serie A and Coppa Italia.
On 3 July 2017, Serie A newcomers SPAL secured a deal for Oikonomou. He joined on loan with an option to buy that would become an obligation if SPAL avoid relegation. On 12 August 2017, he made his debut with the club in a home Coppa Italia 1-0 win game against A.C. Renate.
On 11 January 2018, Bari announced the loan of Greek international from Bologna till the end of the season. This will be the fourth Italian club for the Greek defender. Oikonomou was loaned to SPAL in the beginning of the season, but he did not in the plans of coach Leonardo Semplici, so he moved in Serie B club Bari. On 27 January 2018, he made his debut in a 4–0 home loss game against Empoli.
AEK Athens (loan)
In 2012, Oikonomou was capped by Greece U21s. On 16 March 2016 Oikonomou was called for the first time to play for the senior Greece national football team in two friendly matches against Iceland and Montenegro. On 24 March 2016, he made his debut with the senior side as a substitute for Kostas Manolas in a 2–1 home friendly game against Montenegro.
- As of 8 December 2018
|AEK Athens (loan)||2018–19||6||0||1||0||7||0||–||–||14||0|
- Bologna profile (in Italian) accessed on 12 May 2017
- "Μεγάλη μέρα για το Μάριο Οικονόμου που φόρεσε τη φανέλα με το εθνόσημο". gianninasports.gr. 15 November 2012.
- "Μάριος Οικονόμου: "Νιώθω έτοιμος"". www.passports.gr. 7 July 2013.
- "Στην Μπολόνια ο Οικονόμου". contra.gr. 2 July 2014.
- "Bologna-Cagliari, scambio tra Oikonomou e Capello: il comunicato ufficiale". gianlucadimarzio.com. 1 July 2014. Archived from the original on 28 July 2014.
- "Bologna, sirene dalla Serie A per Oikonomou". tuttomercatoweb.com. 24 November 2014.
- "Oikonomou: "A Brescia non ci accontentiamo, stimolante avere a fianco Gastaldello"". tuttomercatoweb.com. 9 April 2015. Archived from the original on 13 July 2015.
- "Bologna promoted to Serie A". www.football-italia.net. 9 June 2015.
- "Anthony Mounier fires Bologna past Frosinone". www.sportsmole.co.uk. 20 September 2015.
- "Bologna player ratings: Oikonomou's efforts in vain". gazzettaworld.gazzetta.it. 24 September 2015.
- "Bologna renew Oikonomou's contract". www.transfermarketweb.com. 20 October 2015.
- "El Bologna ha renovado a Marios Oikonomou hasta 2020". www.nuevofutbol.com. 20 October 2015.
- "Oikonomou out for a month". www.football-italia.net. 27 October 2015.
- "Frosinone-Bologna 1-0". www.corrieredellosport.it. 3 February 2016.
- "Υπογράφει στην SPAL ο Οικονόμου". www.gazzetta.gr. 30 June 2016.
- "Ανακοίνωσε Οικονόμου η Μπάρι". www.novasports.gr. 11 January 2018.
- "Επίσημο: Στην ΑΕΚ ο Οικονόμου". www.sport24.gr. 28 June 2018.
- "Οικονόμου: «Να χτίσουμε κάτι καλό για το μέλλον»". www.sdna.gr. 24 March 2016.