Sotiris Ninis

Ninis began his career in 2004 as a youngster in Panathinaikos' football academies, joining from the academy of Apollon Smyrnis. On 22 December 2006, the club directors offered him a five-year contract and just two weeks after that day, on 7 January 2007, Panathinaikos coach Víctor Muñoz selected him in the main squad for the match against Egaleo at the Olympic Stadium. His outstanding performance earned him the title of the Superleague Matchday MVP. He became the second youngest player ever to wear the club's shirt in a league match, at the age of sixteen (the first was Kostas Antoniou − 15-years old - in 1978). In February 2007, he officially rejected a call to play for the Albanian Under-21 national team. On 15 February 2007, Ninis became the youngest player to participate with a Greek football team in a European cup match, against RC Lens in France. On 18 February, Ninis lead Panathinaikos in a 4–1 win over rivals AEK Athens in the Olympic Stadium. Ninis scored one goal and assisted two others. On 6 July, Ninis signed a professional contract with Panathinaikos.

The 2007–08 season was marred by injuries and non-selection. After coming on as a substitute against Olympiacos in the first game of the season, Ninis was hit by several injuries, a hamstring injury followed by stomach muscle injuries ruled him out of action for three months. It is thought that these injuries arose due to burnout from playing too many games at a young age. He eventually returned in December, but was not part of the Panathinaikos first team for the remainder of the 2007–2008 season. This decision by Panathinaikos coach Jose Peseiro was heavily criticised by all Panathinaikos fans. Despite this, in December 2007, Ninis won the HFF Young Player of the Year, as voted by fellow players and managers. Ninis is the youngest player to have won this award.

The 2008–09 season began well for Ninis. New manager Henk ten Cate featured Ninis regularly in Panathinaikos' pre-season training. He repaid this faith through his performances against teams such as R. Charleroi S.C. Having entered the pitch at half-time, Ninis assisted three goals and scored one, aiding Panathiniakos to a 5–1 victory against the Belgian club. On 11 August 2008, it was revealed that ten Cate had selected Ninis to be one of the new captains of Panathinaikos, along with fellow players Dimitris Salpingidis and Gilberto Silva. Ninis is the youngest ever player to be chosen as captain of Panathinaikos, at the age of 18 years and 125 days. On 23 September 2008, Ninis extended his contract with Panathiniakos for an additional four years to 2012, with a €10m buy-out clause into the agreement for any foreign team wanting to buy him, rising to €17m for a Greek side.

Ninis was officially called up by Greece coach Otto Rehhagel on 16 May 2008 for the game against Cyprus on 19 May. This was Ninis' first ever senior call-up and offers him a chance to stake a claim for the Euro 2008 squad. Ninis, who impressed as Greece reached the final of last year's UEFA European Under-19 Championship, expressed his delight at the news, saying: "It's a dream come true and an extra motivation to work even harder and improve myself. I'm very happy."

On 8 September 2009, Ninis scored the equaliser against the England U21 team in a match that finished 1–1.

In February 2010, Ninis made his best appearances with Panathinaikos and generally in his personal career so far in the knockout stage of the UEFA Europa League against AS Roma. That days, Roma was in great form and was second in Serie A. Having played well in the first match, in OAKA, he helped his team win 3–2. However, in Stadio Olimpico in Roma, he did better, than any other time before. He won a penalty, which Djibril Cissé converted to equalizer for Panathinaikos, then the Greek young attacking midfielder scored from 28 meters and in the stoppage time of the first half he made a great pass to Djibril Cissé, who didn't have a problem to score.

On 1 June 2010, Otto Rehhagel named his official 23-man squad for the 2010 FIFA World Cup in South Africa. Ninis made the cut despite limited appearances for Greece. He was used twice, as a substitution in the matches against Nigeria and Argentina. He is also the youngest player to have been selected by Rehhagel, at just 20 years of age.

In September 2011, Ninis suffered an injury and did not make his return until March.

On 2 September 2011, Ninis scored the winning goal in a qualifying match for the UEFA Euro 2012 against Israel, in Tel Aviv.

On 20 May 2012, he played his last match with Panathinaikos in the 2011–12 Superleague Greece playoffs final against AEK and was replaced by substitute Giorgos Karagounis in the 70th minute. In total, Ninis made 137 appearances for Panathinaikos, scoring 15 goals.

In March 2012, Parma president Tommaso Ghirardi announced he had signed the Greek midfielder for the summer.

After a disappointing 2012–13 season in which he only made 14 appearances for Parma, Ninis returned to his homeland on-loan to PAOK Salonika. His contract was terminated by mutual consent in August 2014.

On 6 November 2014, Ninis signed a new contract with Panathinaikos for two-and-a-half years.

On 10 September 2017, Ninis signed for one year at Maccabi Petah Tikva of the Israeli Premier League as a free agent, after being released from KV Mechelen a week earlier.

In October 2018, Ninis joined Liga Leumit side Hapoel Ashkelon. On 8 October 2018, he scored on his debut after coming on as a substitute in a 2–1 win over Hapoel Kfar Saba.