Born in Lodz, Poland Janowicz began playing tennis at the age of five after his parents introduced him to the sport. Father, Jerzy, and mother, Anna Szalbot, were both professional volleyball players. Janowicz has named Pete Sampras as his inspiration. Janowicz is currently dating a Polish female tennis player, Marta Domachowska, who has a career-high WTA ranking No. 37.
Janowicz inherits his athleticism and height from his parents, who were both volleyball players. Also his parents were highly aggressive and very susceptible to letting their emotions take control of them, which Janowicz clearly inherits given his many controversial moments on the tennis court. At the age of 10 or 11, his parents sold off their chain of sports stores and apartments to support their son's training, recognizing that he had a future in tennis from a young age. As a junior Janowicz posted a 59–23 win/loss record and reached a combined ranking of No. 5 in the world in 2008. He reached the Boys' Singles final at the 2007 US Open and 2008 French Open, losing in straight sets to Ričardas Berankis and Yang Tsung-Hua, respectively.
2012: Top 30 ATP ranking and breakthrough on ATP World Tour
Janowicz ended 2011 ranked 221 in the world. At the start of 2012 he couldn't play in the 2012 Australian Open due to lack of sponsorship. In February he was the runner up in a Challenger tournament in Wolfsburg, Germany. Later in the year he won three Challenger tournament finals. At the 2012 French Open he got as far as the third round of qualifying, but failed to make it into the actual tournament. At the 2012 Wimbledon Championships, he made it through the three rounds of qualifying to be in the main draw of a grand slam tournament for the first time, where he defeated a qualifier, Simone Bolelli, in the first round, Ernests Gulbis in the second, then lost to the 31st seed Florian Mayer in the third. At the 2012 US Open, he made it directly into a Grand Slam without having to compete in the qualifying rounds. He lost to young American wildcard Dennis Novikov.
In November 2012 Janowicz qualified for the main draw of the 2012 BNP Paribas Masters, an ATP 1000 tournament. He defeated the World No. 19, Philipp Kohlschreiber, in the first round, the World No. 14, Marin Čilić, in the second, and the World No. 3 and Olympic Gold medalist and US Open Champion, Andy Murray, in the third. He defeated Murray in three sets, saving one match point en route. He said afterwards, "This was the most unbelievable day in my life." In the quarterfinals he defeated World No. 9, Janko Tipsarević, to go on to play in the semifinals where he beat Frenchman and World No. 20 Gilles Simon to reach his first ATP tour-level final. He was the first qualifier to do this since Andrei Pavel in 2003 and the first player to reach the final on his ATP World Tour Masters 1000 debut since Harel Levy in 2000. In the final he was defeated by fourth seed David Ferrer, but afterwards said "I've got a lot of confidence right now. I learned if you have big heart and you want to do something amazing and you're going to fight for this, you have a big chance to make it." His run led him to the world's top 30 for the first time in his career, and he finished the year ranked number 24, almost 200 places higher than the previous year.
2013: Ascent to No. 14 and First Grand Slam Semifinal
Jerzy Janowicz at Roland Garros 2013
Janowicz began his season at the Heineken Open in Auckland, New Zealand where he was seeded fifth; however, was knocked out in his opening match against American Brian Baker. He then competed for the first time in the main draw of the Australian Open, where he was the 24th seed, the first time he had been seeded at a Grand Slam tournament. He won his first two matches against Italian Simone Bolelli in straight sets, and Somdev Devvarman of India, against whom he had to recover from a two-set deficit to win in five. In his third round match, he lost to 10th seed Nicolás Almagro in straight sets.
At the French Open, he reached the third round, where he was eliminated in four sets by Stanislas Wawrinka.
At Wimbledon, he defeated Nicolás Almagro for a spot in the round of 16 and Jürgen Melzer for a spot in his first career Grand Slam quarterfinal. He then beat fellow Pole Łukasz Kubot in straight sets, becoming the first Polish man to reach a Grand Slam semifinal. There, he was beaten by World No. 2 and eventual champion Andy Murray in four sets.
Jerzy performed disappointingly in US Open, falling to world No.247 Maximo Gonzalez in straight sets, suffering from a back injury. His back injury caused him to withdraw from next few tournaments. He returned in October to reach quarterfinal at Stockholm Open, where he lost to Ernests Gulbis in three sets, a player he had won with in previous year's Wimbledon in a long five set match. Then he traveled to Valencia Open reaching quarterfinals as well, where he lost to eventual runner-up David Ferrer.
Janowicz's last tournament of the year was Paris Masters, where he made a breakthrough last year. He won his opening meeting with Santiago Giraldo, but did not defend points due to his loss to No.1 seed Rafael Nadal. Janowicz finished the season at No.21.
Janowicz is one of the fastest servers in game, hitting a first serve generally between 130 and 140 mph and often hitting a second serve from 115 to 120 mph. His ball toss is extremely high, even for a man who is 6 ft 8, producing a high trajectory. Janowicz also moves remarkably well considering how big he is, and hits powerful groundstrokes from the back of the court and has an excellent drop shot. He has a double handed backhand, and is known to hit hard and constantly mix up his game by hitting numerous drop shots, slices and spins.
Won tournament; or reached Final; Semifinal; Quarter-final; Round 4, 3, 2, 1; competed at a Round Robin stage; lost in Qualification Round; absent from tournament event; played in a Davis Cup Zonal Group (with its number indication) or Play-off; won a bronze, silver (F or S) or gold medal at the Olympics; a downgraded Masters Series/1000 tournament (Not a Masters Series); or a tournament that was Not Held in a given year.
To avoid confusion and double counting, these charts are updated either at the conclusion of a tournament, or when the player's participation in the tournament has ended.