Mark Samuel Knowles was born on September 4th, 1971 in Nassau, Bahamas. His parents were tennis pros at one of Nassau's tourist resorts and Mark started playing at the age of four under the guidance of his parents. At the age of ten, he was invited to train at Nick Bollettieri's famed tennis academy in Bradenton, Florida. When Knowles was fifteen, he became the U.S. Indoor 16's champion in the singles tournament as well as finishing as the runner up in doubles.

Knowles attended UCLA, where he earned All American honors, before he finally started on the pro tour in 1991. He partnered with Daniel Nestor in 1994 and they won the first tournament they entered in Bogota. Knowles and Nestor found their partnership to have success, and it showed as the duo reached the second week of the slams in doubles for the next few years, including three runner up finishes.

In December 2001, Mark launched the first Mark Knowles Tennis Celebrity Invitational in Nassau to support different Bahamian charities. In 2002, Knowles and Nestor won the first of their three Grand Slam doubles titles at the Australian Open. They also made the finals at Roland Garros and Wimbledon that year. In June, Mark reached No. 1 in the world, becoming the first Bahamian to achieve the milestone. Two years later, Knowles and Nestor won the U.S. Open. The two captured the French Open in 2007 and ended one of the most successful partnerships in history by winning the year end Masters Cup in Shanghai that same season.

Mark played his 2008 campaign with Mahesh Bhupathi. They reached the semifinals at the Australian Open, defeating the Bryan Brothers in a classic quarterfinal match, and they captured their first title together in Memphis. They finished the year strong, finishing runner up in Madrid and winning Basel. The title in Basel gave Mark his 50th career doubles title, which ranks up there with the all time greats. Additionally, he is one of a few athletes to be a five-time Olympian, which he achieved by participating in the Beijing Olympics.

He continued his partnership with Mahesh for the 2009 season and the two won the Masters Series event in Canada and reached the finals of both the Australian Open and US Open. Mark also won the title in Memphis with Mardy Fish and those two signed on to join forces for the 2010 season after a mutual decision by Mark and Mahesh to end their partnership.

With Fish, Mark captured the Legg Mason Tennis Classic in Washington and advanced to the third round of the US Open. He finished his season off by partnering Andy Ram to a runner-up finish at the Masters 1000 event in Paris, where the two knocked off the Bryans in the quarterfinals.

Mark will play with Slovakian Michal Mertinak in 2011.

Knowlzee married Dawn Davidson in 2003, and they have two sons, Graham, five and Brody, two, and one daughter, Presley, six months.