Mario was born in Split to Stipe and Nilda Ančić. His father owns a supermarket chain, and his mother is a financial adviser. His older brother, Ivica, and younger sister, Sanja were also professional tennis players. Ivica achieved a career high ATP Ranking of 378 in 1997, while Sanja, was a world top 10 junior in 2005 and achieved a ranking of 159 on the WTA Tour in 2006. Mario split from his long term girlfriend, Dolores Goleš, in 2009. From 2002 to 2008, Mario was a law student at the University of Split; he graduated from its law school on April 14, 2008, with a thesis entitled "ATP Yesterday, Today and Tomorrow", describing the legal foundation and organization of the ATP Tour. Illness forced Ančić to be off courts in much of the 2009 tennis season, and he started his residency in the lawyers office of Turudić in Zagreb; but he announced he will freeze his residency for some time due to his tennis career. In 2009 he spoke two times at the Harvard Law School about his law and tennis experiences, and the second time about doping cases in tennis. Ančić grew up two doors over from the Firule tennis club, where he started playing at age seven. From age 10 on, Mario practiced there with Goran Ivanišević, with whom he played doubles matches later in his career. In 1996, he served as a ball boy when Ivanišević played in the Croatia-Australia Davis Cup tie in Split.As a junior player, he rose to No. 1 in the junior world-rankings, on January 2, 2001. He made the finals in boys' singles at the 2000 Australian Open (losing to Andy Roddick) and the 2000 Wimbledon Championships (losing to Nicolas Mahut). Ivanišević was his doubles partner in both his Croatian Davis Cup Team debut and at the 2000 Summer Olympic Games in doubles. The duo lost in the opening round at the Olympics. At first, Mario mostly played Futures and Davis Cup tournaments, winning one title in Zagreb; and from August 2001 he started to play Challenger tournaments, wining four in singles and one in doubles. He compiled a record of 30-16 in Challenger play in 2002.
Video from Mario Ancic
Ančić started on the 2006 ATP Tour with strong note in his second tournament of the year at Auckland, where he defeated top seed Fernando González on his way to the final. However, he could not repeat his form in the final, going down in straight sets to Jarkko Nieminen. In February, he also reached final at Marseille, losing to Arnaud Clément. He made in quarter-finals at two Masters and two Grand Slams tournaments. Mario was defeated two times by David Nalbandian, at Miami and Rome; and two times by Roger Federer, at Grand Slams, French Open and Wimbledon. He also reached his career high at Master Series event, reaching into semi-finals at Hamburg Masters. A week before Wimbledon, Mario successfully defended his 2005 title at ‘s-Hertogenbosch. After Wimbledon, Mario reached No. 7, his career high in singles. At the 2006 French Open, he had a shoving incident with Paul Capdeville at the end of his second round match. Ančić was bothered by the Chilean's repeated complaints to the chair umpire, including just before the post match handshake, Ančić told Capdeville to drop it, after that Capdeville shoved Ančić. Both of them were fined $3,000. Ančić missed the US hard court season, due to a knee injury received in a jet skiing accident, and just before the 2006 US Open, a back injury. In September, in the first event after the summer injuries, he reached final at China Open, losing to Marcos Baghdatis. Mario also teamed-up with Mahesh Bhupathi, and won two doubles titles in Beijing and Mumbai. In October, he won his third singles title, at St. Petersburg Open. At Paris Masters, Ančić lost to Nikolay Davydenko, in the quarterfinals. If Ančić had won, he would have secured the final spot in the field, narrowly missing a spot in the eight-man Tennis Masters Cup in Shanghai.
After a successful 2006 season, Ančić began the year by representing Croatia with his younger sister, Sanja Ančić, at the 2007 Hopman Cup, but they did not advance from the group stage. He then entered the 2007 Australian Open as the ninth seed, and advance to a fourth round, where he played against Andy Roddick, seeded sixth. He lost the match, after Roddick broke Ančić in the fifth game of the fifth set, then held that advantage, serving out the match and winning with the final result 3–6, 6–3, 1–6, 7–5, 4–6. At Marseille, Ančić retired in the first round, and was diagnosed with mononucleosis, also known as glandular fever. Later, he confessed that he was playing sick a week before in a match against Germany in the Davis Cup, and the virus had almost certainly started to affect him at the Australian Open. Due to his illness, Ančić spent most of the next ten weeks in bed, and missing six months from the Tour. Ančić started training in June with his Swedish coach, Fredrik Rosengren, in the Slovenian Alps; and after he withdrew from two tournaments in July, Mario returned in August at Canada Masters and at Cincinnati Masters, where he lost in the second rounds. He was offered a wild card for main draw in the Pilot Pen Tennis tournament in New Haven, but he turned it down with the explanation that he needed matches. Mario fractured a small bone at the gym a week before the US Open, which was his third Grand Slam to miss in 2007. In October, he made his first big result after the illness, into the quarter-finals at Madrid Masters beating on the way No. 8 seed James Blake and Paul-Henri Mathieu, before losing to Novak Djokovic in straight sets. In 2007, he dropped 74 places, from number 9 to number 83 at the end of the 2007 ATP Tour.
Ančić started the 2008 season again with illness, and was forced to withdraw from the tournaments in Australia, and missed his fourth Grand Slam in a row. His first 2008 event was at Marseille in February, where he beat the 2008 Australian-Open finalist Jo-Wilfried Tsonga and also Marcos Baghdatis. He eventually lost in the final to Andy Murray. At the Indian Wells Masters and Miami Masters, Mario entered the main draw by receiving a wild cards, where he beat three seeded players. Like in 2006, he was beaten by Roger Federer two times, at the French Open in the third round, and at Wimbledon, where he reached a quarter-final. On the way to the quarter-final, he beat No. 32 seed Michaël Llodra, No. 5 seed David Ferrer, and with a comeback win against No. 22 seeded Fernando Verdasco in the fourth round, coming from two sets down to win 3-6, 4-6, 6-3, 6-4, 13-11. By reaching the quarter-final, he jumped 19 places, to No. 24 on the ATP singles rankings. In doubles, he won his fifth title at s'Hertogenbosch with Jürgen Melzer. Having lost in an opening-round at the Canada Masters and having skipped Cincinnati Masters, as the fatigue intensified and the weight loss mounted, Mario withdrew from the 2008 Summer Olympics, and later the US Open, due to a recurrence of mononucleosis. Ančić returned in September, playing for the Davis Cup. After a good start at beginning of the 2009 season, in May, Ančić announced he will pull out of the French Open, Wimbledon and Davis Cup semifinal match, again because recurrence of mononucleosis. Ančić announced in October 2009 that he plans to start at the end of January 2010 on a couple of European ATP Challengers. His best result was a runner up spot in a futures event in the USA. Mario's comeback was complete when he returned to the main tour level at the 2010 BNP Paribas Open, he made it to the third round after beating, Bobby Reynolds and surprisingly Julien Benneteau, and lost to Nadal 6-2, 6-2. He didn't have so much success the week after at the Sony Ericsson Open when he lost in the first round to Jérémy Chardy. Ančić continued to play challengers without success. He also lost a tight first round match to Koellerer in a 250 event in Munich. He then received a wild card to Queen's on his favoured surface of grass.