Bart attendedBuford High School inBuford, Georgia.[1] He became the startingcatcher for the school's baseball team in his freshman year. He had a .556on-base percentage and a .859slugging percentage in his junior year, but was pitched around by opposing teams in his senior year, decreasing his performance. Buford HS won the Georgia Class 4A State Championship his senior year going 34–2 and finishing ranked as 8th in the MaxPreps National Poll. TheTampa Bay Rays selected Bart in the 27th round of the2015 Major League Baseball draft, but he opted not to sign.[2]
Due to the layoff following the college season, the Giants sent Bart to theirScottsdale, Arizona, facility, before assigning him to theSalem-Keizer Volcanoes of theClass A Short SeasonNorthwest League.[19][20] In 45 games and 181 at bats for Salem-Keizer, Bart slashed .298/.369/.613 (leading the Northwest League) with 13 home runs (3rd) and 39 RBIs (5th), as he also was second in the league in hit-by-pitch, with 9.[21][22] He was named an NWL mid-season All Star, a NWL post-season All Star, aBaseball America Short-Season All Star, and a 2018 MiLB.com Organization All Star.[23]
The Giants again invited Bart to spring training in 2020.[31] With the 2020 minor league season cancelled due to theCOVID-19 pandemic, the Giants assigned Bart to their alternate training site.[32]
On August 20, 2020, Bart was promoted to the major leagues for the first time.[33] He made his debut that night against theLos Angeles Angels and got his first career hit, a double off ofJulio Teherán.[34] Bart recorded anextra-base hit in each of his first three career games, only the third Giants player to do so since at least 1901.[35] He finished the season slashing a weak .233/.288/.320 in 33 games.[36]
On May 4, 2021, Bart was called back up to the majors from one of the Giants alternate training sites.[37] He had one at bat as apinch hitter in the Giants' second game of the double header against theColorado Rockies.[38] Two days later, Bart was optioned to theSacramento River Cats to start theTriple-A season.[39] On July 10, due to the hand injury ofBuster Posey, the Giants called Bart up again after he was hitting over .335 with an OPS of over .980.[40] Bart hit seventh and caughtAnthony DeSclafani while going 2–5 with two singles and an RBI.[41] The following day, Bart was optioned back down to Triple-A Sacramento during the All-Star break.[42]
Bart began the 2022 season with San Francisco, and hit his first career home run off ofMiami Marlins starterSandy Alcántara on April 8.[43] Bart struggled in his brief look and was optioned down to Triple-A Sacramento on June 8, after the Giants traded forAustin Wynns.[44] Playing in a career–high 97 games, Bart again had difficulty keeping up with the bat, as he slashed .215/.296/.364, to go with 11 home runs and 25 RBI.[45]
Bart made theOpening Day roster for the Giants in 2023, but ceded starting duties toRoberto Pérez to begin the year.[46] After Pérez underwent season-ending surgery on April 13, Bart assumed the starting role, withBlake Sabol serving as the backup.[47] Bart hit .231 in 26 games before being placed on the injured list on May 19 with a groin strain.[48] Upon being activated on June 10, Bart was optioned to Triple–A Sacramento in favor ofPatrick Bailey, leaving Bailey and Sabol as the starting and backup catchers.[49] In 30 games for San Francisco, Bart batted a very weak .207/.263/.264, with no home runs and only five RBIs.
On April 2, 2024, the Giants traded Bart to thePittsburgh Pirates in exchange for Austin Strickland.[53] He began competing withHenry Davis for playing time, asJason Delay andYasmani Grandal were injured.[54] Across 80 games for the Pirates in 2024, Bart batted .265/.337/.462 with 13 home runs and 45 RBI.[55]
In 2025, Bart won the starting catcher job out of spring training, but was injured on May 28th with a concussion.[56] After Bart came back from his injury, he split time behind the plate with Davis, winding up with a .249/.355/.340 slash line. Bart hit just 4 home runs and had 30 runs batted in.[57]