FC Argeș Stancu was discovered at a trial by coach Mihai Ianovschi in 1998, who took him to the junior team of
Argeș Pitești. In 2001, at the age of 14, Stancu was at the
youth academy of
FC Argeș when his father died due to heart failure. He was deeply affected by the loss and quit football for a few months. In 2005, he was brought to the first team by
Sorin Cârțu. After a short period he was sent to
Dacia Mioveni in
Divizia B, where he had a contract of only
$1000 per month and a clause by which he earned
$1 for every minute played for
Mioveni. His team won a few games with Stancu as their only goalscorer. After a season where he scored 3 goals in 12 matches, he returned to FC Argeș and made his debut in
Divizia A at the age of 19 against former champions
Steaua București, game which ended as a goalless draw. In the summer of 2006, Sorin Cârțu resigned from the club and former Italian star
Giuseppe Giannini was appointed as the new manager of Argeș Pitești. After two weeks of training he decided that Stancu and another player,
Robert Neagoe, should be released. He ended up making only seven appearances for his team that season. Stancu was sent once again to
Dacia Mioveni during the pre-season but after a few days, Gigi Nețoiu brought him to
Unirea Urziceni. In May 2008, after three years at Unirea, Stancu was transferred to Steaua București. Local media reported the fee to be in the region of
€1 million.
Steaua Bucharest 2008–09 season On 30 June 2008, Stancu played his first match in Steaua's shirt in a friendly against
Maribor, scoring the first goal. He scored his second goal On 26 July against
Roma in a friendly game, Steaua won 3–1. On 23 August 2008, Stancu scored his first double for Steaua against
Gloria Bistrița in
Liga I. In his first five Liga I matches for Steaua he scored four goals. He managed to score four goals in several winter break friendly matches. After the winter break he scored again in the first match against
Vaslui. On 14 March 2009, he scored in the sixth minute of the match against
Politehnica Iași, leading Steaua to its victory. At his first season at Steaua was top scorer with 11 goals, along with Greek
Pantelis Kapetanos.
2009–10 season Stancu started the new season scoring the second goal for his team against
Újpest in the second qualifying round of
UEFA Europa League, on 16 July 2009, making the score 2–0 for
Steaua București. He scored the third and final goal against
Motherwell after being served perfectly by
Rafał Grzelak. On 6 August 2009, he scored two more goals against the same Motherwell and help his team qualify in the Europa League playoffs. After his great performances in Europa League he was rewarded by
Răzvan Lucescu with a call-up in the
Romania national team against
Hungary. However, during a league match he got injured and Lucescu dropped him from the team. Two weeks later he scored another two goals against
St Patrick's Athletic. In nine European matches he scored six goals. He was sent off on round 4 against
Oțelul Galați in the 75th minute after receiving a second yellow card. At end of season he was top scorer of team in Europa League with six goals.
2010–11 season On 25 July 2010, Stancu netted the second goal in his first start of the season in a 1–2 away win against Universitatea Cluj. In the second round he scored the equalizer in the 66th minute against
Universitatea Craiova, after
Valentin Iliev opened the score, 12 minutes later his teammate
Romeo Surdu, scored the second goal helping the team to a 2–1 home win. In the 4th round he scored twice against
Victoria, first goal in 24th minute and the victory goal in the 67th minute, Steaua winning home with 2–1. In his first European match of the season he scored the only goal in a 1–0 match against
Grasshoppers. In the 5th round he scored against
FC Vaslui, he scored second goal of the match in 46th minute, Steaua winning with 3–0. On round 10 scored two goals against
Sportul Studențesc in a 4–2 victory. On next two rounds scored three goals, one against
Dinamo București and two against
Pandurii Târgu Jiu in a 2–0 victory. In
matchday 4 at Europa League, Stancu scored two goals against
Utrecht in a 3–1 victory, both goals came in the 52nd and 53rd minute. On round 17, Stancu scored twice against
CFR Cluj. The next match day Stancu scored again in a 3–0 win against
Universitatea Cluj.
Galatasaray On 21 January 2011, Stancu was sold to Turkish club
Galatasaray for
€5 million. He signed a four-and-a-half-year contract worth
€5,2 million He scored on his first Turkish Cup match for Galatasaray, a 3–2 loss against
Gaziantepspor in the first leg of the
2010–11 Turkish Cup quarterfinals which he had scored the second goal with a long shot. Stancu then scored in his second regular match in the
Turkish League too, in the 4–2 win against
Eskişehirspor. On the ninth of May Stancu scored a goal in Galatasaray's victory against
Kasımpaşa. He finished the season with 3 goals in 16 appearances.
Orduspor On 23 August 2011, Stancu was loaned to
Orduspor on a one-year loan deal worth
€350,000.
Fatih Terim decided to start the 2011–12 season with the newly arrived striker
Johan Elmander and
Milan Baroš. He scored four goals in his first seven games for Orduspor. In the last week of January 2012 he was chosen player of the week in the
Süper Lig by Gazete Futbol due to his performance against
Eskişehirspor. On 1 February he opened the score in a match against
Ankaragücü. He continued his goalscoring form by scoring in the 3–2 victory against
Antalyaspor on 12 February. On 11 March Stancu scored a goal in a game against
Beşiktaş to eventually earn a draw for Orduspor. Then he assisted
Javito's goal, in a game against
Sivasspor, which finished in a 1–1 draw. At the end of the year Stancu joined Orduspor for a fee of
€2.5 million. He later signed a four-year contract worth
€1.2 million per year.
Gençlerbirliği On 25 July 2013, after Orduspor was relegated from the
Süper Lig Stancu moved to
Gençlerbirliği for an undisclosed fee. the last of which was against his former club
Galatasaray.
Bursaspor On 19 January 2017, it was reported that he signed a two-and-a-half-year deal with
Bursaspor.
Return to Gençlerbirliği On 21 January 2019, he returned to former club he signed a one-and-a-half-year deal he wore number 17 on his return and in 2019–20 season he switched to number 9 shirt.
Eyüpspor On 18 June 2021, Stancu signed a 1+1 year contract with
Eyüpspor. ==International career==