In 2003, Bolelli reached his first ITF Futures tournament semifinal at Egypt F1, losing to 485th-ranked Jaroslav Pospíšil. He played entirely Futures events except for one Challenger tournament in Brindisi, losing to Galo Blanco in the second round. He finished the year ranked 623.
2004 saw Simone reached his second Futures final, losing to Dominique Coene. He then made another final and won two Futures titles, making a 2 wins out of 3 finals record for Futures finals in the 2004 season. He won the Italy F15 and F8 titles, and lost in the final of a Challenger event in Braşov. In doubles, Bolelli won the doubles Futures title with Alberto Brizzi at Italy F15, and with Brizzi at Italy F8, winning both the singles and doubles events at F15 and F8. He finished ranked no. 269 for singles and no. 533 for doubles.
Bolelli did not win a Futures tournament in 2005 for singles; however, he did reach the final of a Challenger in Trani. Simone's doubles success in 2005 was also limited: he did not reach any type of final.
Simone Bolelli played in a few tournaments higher than a Challenger, receiving a wildcard into the Rome Masters. He lost in three sets to no. 39 Fernando Verdasco. He also won the Como Futures tournament and made the final of Recanati, before losing to Davide Sanguinetti. He won his first Challenger singles title over Ivo Minář, and then made the final of a Challenger in Bergamo where he lost to Alex Bogdanović. He also played Fernando González in Basel (entering the tournament as a Lucky Loser), taking the second set in a tiebreak and losing the surrounding sets in tiebreaks. Bolelli qualified and lost in the first round of Vienna to number 27 Dominik Hrbatý. He lost in Stuttgart to Jiří Novák, having played 4 ATP matches and winning a set in 2 of them. Partnered with Fabio Fognini, Bolelli lost in the finals of the Naples Challenger doubles tournament in March. Simone won the Rencanati doubles tournament with singles champion (who defeated Bolelli in the final), Davide Sanguinetti, and reached the quarterfinals of the Monte Carlo Masters partnering Andreas Seppi, winning three-set matches over Igor Andreev and Nikolay Davydenko and then Leoš Friedl and František Čermák. They eventually lost to Fabrice Santoro and Nenad Zimonjić. He finished the year ranked in the top 200, ranked world No. 127 for singles and world No. 171 for doubles.
In qualifying for the 2007 Australian Open, Bolelli was seeded 15th, but lost in the second round. Bolelli lost to Fabrice Santoro in the Bergamo Challenger and boasted a career win over no. 22 Dmitry Tursunov at the Miami Masters, before losing to David Ferrer. He won one singles Davis cup match versus Israel, but then lost to Noam Okun. He lost in the Casablanca Challenger final to Marin Čilić and winning his own in Tunisia over Andrei Pavel in three sets. Simone beat former world no. 1 Marat Safin in Barcelona and competed in the Miami, Rome and Hamburg Masters. He made his Grand Slam debut at the 2007 French Open, beating former runner-up Martin Verkerk, and then losing to Guillermo Cañas. At Wimbledon, he beat Guillermo García-López, before losing to former world no. 1 Lleyton Hewitt. He lost in the first round of doubles competition on both occasions, both times partnering with Juan Martín del Potro.
Bolelli was banned by The Italian Tennis Federation from national team events for skipping the Davis Cup tie with Latvia in Europe-Africa zone relegation playoff. The ban prevented Bolelli from playing in Davis Cup competition and the Olympics. It also prevented him from getting wild cards. Bolelli said that he had told Italy captain Corrado Barazzutti well in advance of the tie that he preferred to work on his fast-court game in Asia.
Bolelli represented Italy along with Flavia Pennetta in the Hopman Cup. He won two out of three matches, the loss being to former world no. 1, Marat Safin. He defeated Gilles Simon in straight sets, his first win over a top-10 player. In the Medibank International, he defeated compatriot Potito Starace in the first round, before falling to third seed Jo-Wilfried Tsonga in straight sets.
At the Australian Open, Bolelli beat Kristof Vliegen in three tight sets in the first round. In the second round, Bolelli lost to the 23rd seed Mardy Fish. In the ABN AMRO tournament in Rotterdam Bolelli face world no. 1 Rafael Nadal in the first round. Bolelli won the first set 6–4, but this was not enough, and Nadal won in a tight three-set match.
In July, Bolelli lost to David Ferrer in the third round of the Swedish Open.
After missing the Australian Open, Bolelli qualified for the French Open and made it to the second round before losing to fifth seed David Ferrer in straight sets. He gained entry to Wimbledon as a lucky loser and beat 22nd seed Philipp Kohlschreiber in the second round, before losing to 10th seed Kei Nishikori in the third round in a five-set match.
At the US Open, Bolelli beat Vasek Pospisil in the first round in five sets, but then lost to 16th seed Tommy Robredo in another five-set match.
At the 2015 Mutua Madrid Open, Bolelli defeated 15th seed Kevin Anderson and qualifier Luca Vanni to reach the third round, where he lost to Rafael Nadal.
Current till 2017 US Open.
* 2009 Wimbledon Championships counts as 1 win, 0 losses. Jo-Wilfried Tsonga received a walkover in the second round, after Bolelli withdrew.