Varitek played in the 1984 Little League World Series. His Altamonte Springs, Florida, team lost in the finals to Seoul, South Korea, by a score of 6-2. Varitek played shortstop, thirdbase, and catcher in his three LLWS games. He was hitless going 0-7. Varitek was 12 years old at the time, while most of his teammates and competition were 13.

While in high school, Varitek was a third baseman and catcher for the Lake Brantley High School baseball team in Altamonte Springs, FL. The Patriots' usual catcher was Jerry Thurston, himself a major league prospect. In 1990, the Patriots won the state championshipand were later named as the number one team in the nation, by USA Today.

Varitek then went on to Georgia Tech, where he played with future teammates Nomar Garciaparra, Darren Bragg and Jay Payton, and took part in the 1992 Summer Olympics. During his senior season in 1994 , he played in the college baseball national championship game. After his senior season, Varitek won three collegiate baseball awards: the Dick Howser Trophy, the Golden Spikes Award and the Rotary Smith Award, each recognizing the outstanding collegiate baseball player in America. He was the first baseball player in school history to have his number retired.

Varitek played two seasons in the Cape Cod League with the Hyannis Mets. In 1993 he hit .371 while winning both the league batting championship and MVP. He was drafted 21st overall in the first round by the Minnesota Twins in 1993[5], but opted to return for his senior year of college. Following graduation, Varitek signed with agent Scott Boras and was drafted by the Seattle Mariners in the first round of the 1994 amateur draft, with the 14th pick overall[6]. A pioneer of the loopholes in the draft process, Varitek signed with the St. Paul Saints in the independent Northern League[7] before agreeing to terms with the Mariners, and consequently did not enter the Mariners' minor league system until 1995. When he finally did join the franchise, Varitek was sent to the AA affiliate Port City Roosters where he first meets longtime teammate Derek Lowe. He was traded with pitcher Derek Lowe to the Red Sox during the 1997 season, in return for reliever Heathcliff Slocumb, often cited as one of the best trades in the Red Sox's favor in recent history.

Varitek was called up for a single game on September 24, 1997, collecting a single in his only at bat. The next season Varitek split time with incumbent catcher Scott Hatteberg playing in 86 games. Varitek showed signs of things to come in the 1998 season and with a strong spring training following the season, Varitek ensured himself the starting role. 1999 was a breakout year for the young catcher; he played 144 games in that season while hitting for a .269 average, with 20 home runs, and 76 RBIs. 1999 also gave Varitek his first taste of the playoffs. Varitek went 5-21 with 3 RBI in the ALDS against the Cleveland Indians and 4-20 with 1 RBI in the ALCS against the New York Yankees. Varitek looked forward to building on his success from the year before, but in 2000 he did not show the same potential and had a disappointing offensive output. He hit just .248 with only 10 homeruns and 65 RBI[8]. Prior to the 2001 season, Varitek signed a 3 year $14.9 million contract with the Red Sox, and off to a hot start before he was sidelined for the season with a broken left elbow after he dove to catch a foul ball on July 7. The play went on to be a top Web Gem for the month of July in 2001. Varitek finished the season with a .293 average, 7 homeruns, and 25 RBI in just 51 games played. Stretched out over a season, this would lead to over 20 homeruns and 75 RBIs, in line with his 1999 season, encouraging the Red Sox front office.

Varitek returned to the Red Sox lineup fulltime in the 2002 season. The return did not go smoothly, however, as Varitek struggled to find himself at the plate. Despite not reaching his full offensive potential, pitchers and coaches alike began to notice how much Varitek's preparation and knowledge of the game was helping the pitchers. His study habits and extra hours of work with pitchers would soon become his defining attribute and make him a household name around the league. Varitek and the Red Sox entered the 2003 season with a renewed fire to reach the playoffs after missing in the previous three years. Varitek instantly became a leader in the working class clubhouse featuring new faces such as Kevin Millar, David Ortiz, Bill Mueller, and Todd Walker along with original Dirt Dogs Trot Nixon and Lou Merloni. 2003 was Varitek's best year to date and earned his first all-star selection after the fans voted him on with the "All-Star Final Vote". He was hitting .296 with 15 HRs and 51 RBIs going into the all-star break and finished the season off with a solid .273 average, 25 HRs and 85 RBIs, all career highs. Varitek also led the Red Sox to a Wild Card birth and their first playoff appearance since 1999.

In 2004, Varitek compiled a career-high .296 batting average with 18 home runs and 73 RBI as his team won its first World Series victory in 86 years. At the end of the year, Varitek became a free agent and signed a 4-year, $40-million contract with the Red Sox.

After Varitek's re-signing, the Red Sox appointed him to be the third team captain in since 1923, after Carl Yastrzemski (1969-83) and Jim Rice (1986-89).

--Wikipedia