Kazmir was born and raised in the Houston, Texas area and gained the attention of MLB scouts as a award-winning multi-sport high school athlete.

He was one of the top pitching prospects in 2004 when the Mets sent him to the Tampa Bay Devil Rays in a trade deadline deal that has been listed as one of the most lopsided in recent major league history.

He returned to the majors with the Cleveland Indians in 2013 and placed third in voting for American League Comeback Player of the Year after winning ten games.

He then signed a two-year contract with the Oakland Athletics and continued his resurgence, as he was named an All-Star and earned a career high 15 wins in 2014.

The A's dealt Kazmir to his hometown Houston Astros at the 2015 trade deadline, and he signed a three-year, $48 million contract with the Los Angeles Dodgers after the season.

Kazmir won 10 games for the Dodgers in 2016, but a series of injuries kept him out of the big leagues for the final two years of his contract, and he remained unsigned in 2019.

Also in 2021, Kazmir was selected as a member of the United States national baseball team for the Summer Olympics in Tokyo, where he started and won the quarterfinal game.

[7][1] The Devil Rays sent Kazmir to their Class AA affiliate, the Montgomery Biscuits of the Southern League, where he started four games, throwing 25 innings and allowing 14 hits while striking out 24.

On June 22, 2006, Scott Kazmir passed Sandy Koufax and put himself in the 22nd spot in MLB history for most strikeouts by a left-handed pitcher before his 23rd birthday.

The next day, he threw his first (and thus far only) complete game shutout, blanking the Boston Red Sox in Tropicana Field on 2 hits while striking out 10.

In the All-Star Game, Kazmir threw a perfect sixth inning, retiring Freddy Sanchez, Carlos Beltrán, and Albert Pujols.

[13] In their year-end review, Baseball Prospectus proclaimed, "Health permitting, he’s one of the best pitchers in the AL."[14] It was also during this time that Tampa Bay fans began crowning Kazmir with the nickname "Pizza Man" which was a reference to a longstanding promotion at Tropicana Field where if the Rays pitching staff combined for 10 strikeouts during a game, attendees of the game could trade in their ticket stub for a free pizza at participating Papa John's restaurants.

[20] Kazmir was less effective over the second half of the season, posting a 5–3 record and 4.02 ERA as the Rays won their first American League East championship.

Angels manager Mike Scioscia said that Kazmir's struggles were "baffling" and that, despite a rigorous off-season training regimen, the former all-star pitcher had lost his velocity, command, and confidence.

[40] Kazmir signed a minor league contract with the Cleveland Indians on December 21, 2012, and received an invitation to spring training.

[12] The A's were not in serious contention for a playoff spot as the trade deadline approached, and Kazmir was rumored to be a potential acquisition target for several teams seeking to improve their starting pitching.

[51] Kazmir won his debut with the hometown Astros, going seven innings and giving up three hits with three strikeouts in a 4–0 victory over the Kansas City Royals.

[58] Coming into spring training, Kazmir continued to struggle with the hip and intercostal injuries which had affected his mechanics during the previous season.

[67] Kazmir made four rehab appearances for the Class A+ Rancho Cucamonga Quakes in August and September, pitching to a 4.50 ERA in 12 innings of work.

His pitch velocity had not increased, however, so the Dodgers decided not to add him to the major league roster for the end of the regular season or the team's playoff run to the 2017 World Series.

[68][57][69] On December 16, 2017, the Dodgers traded Kazmir, Charlie Culberson, Adrián González, Brandon McCarthy, and cash considerations to the Atlanta Braves for Matt Kemp.

[61] His fastball velocity was sitting in the high-80s early in spring training, putting him in the running to be the Braves' fifth starter, but slipped back into the low-80s as the regular season approached.

[71][69] After being removed early from his final scheduled spring training start on March 24 due to a "fatigued arm", the Braves released Kazmir, making him a free agent.

[72] Kazmir continued to work out and began a throwing program soon after his release by the Braves but commented that "it just didn’t turn out too well physically" and paused the workouts.

[77] The Giants sent him to the Triple-A Sacramento River Cats on June 11, though he soon left the minor league club when he was chosen as a member of the United States Olympic baseball team.

[80] In July 2021 while pitching in the Giants' minor league system, Kazmir was selected to play on the United States national baseball team at the 2020 Summer Olympics, which were held in 2021 in Tokyo.

[81] Kazmir appeared in one game at the Olympics, starting against the Dominican Republic in the quarterfinals and pitching five scoreless innings to earn the win.

His fastball was regularly clocked in the mid to high 90s with excellent command, and his preferred strike-out pitch was his slider, which many scouts and other observers compared to that of Hall of Famer Steve Carlton.

His fastball velocity dropped until topping out in the mid-80s in 2011,[87][88] and he "lost his feel" for the slider, using it only sporadically and with poor results after his early 2008 stint on the disabled list.

[91][92] By late in the 2016 season, his fastball velocity had slipped back down to the low 80s, decreasing the difference between the speed of his pitches and reducing his effectiveness.