The Oakland Athletics selected Mondou in the 13th round, with the 382nd overall selection, of the 2016 MLB draft.[4] He spent his first professional season with the Low-A Vermont Lake Monsters, also playing in 1 game for the rookie-level Arizona League Athletics. In 60 games with Vermont, Mondou hit .298/.376/.364 with no home runs, 24 RBI, and 6 stolen bases.
In 2017, Mondou split the season between the Single-A Beloit Snappers and High-A Stockton Ports, batting a cumulative .287/.367/.381 with 2 home runs, 59 RBI, and 16 stolen bases across 125 games.[5] He played in 136 games split between Stockton and the Double-A Midland RockHounds in 2018, slashing .279/.356/.399 with career-highs in home runs (8) and RBI (75) paired with 10 stolen bases. In 2019, Mondou spent the year with Midland, playing in 122 games and hitting .248/.344/.333 with 5 home runs, 45 RBI, and 7 stolen bases.[6]
He did not play in a game in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.[7] Mondou spent the 2021 season with the Triple-A Las Vegas Aviators, playing in 87 games and hitting .283/.371/.432 with 8 home runs and 49 RBI.[8] He returned to Las Vegas in 2022, making 108 appearances and slashing .283/.374/.431 with 7 home runs and 64 RBI.[9]
On October 3, 2022, Mondou was selected to the 40-man roster and promoted to the major leagues for the first time.[10] He made his MLB debut the next day in a game against the Los Angeles Angels, going 0-for-2 with a walk.[11] On November 3, Mondou was removed from the 40-man roster and sent outright to Triple-A.[12] He elected free agency following the season on November 10.[13]
Chicago White Sox
On January 31, 2023, Mondou signed a minor league contract with the Chicago White Sox organization. [14] He was assigned to the Double-A Birmingham Barons to begin the year, where he went 1-for-5 with a home run in two games.[15] Mondou was promoted to the Triple-A Charlotte Knights after Lenyn Sosa was recalled to the White Sox.[16] He played in 116 games for Charlotte, batting .270/.379/.434 with a career–high 13 home runs, 61 RBI, and 7 stolen bases. Mondou elected free agency following the season on November 6.[17]
San Diego Padres
On December 8, 2023, Mondou signed a minor league contract with the San Diego Padres.[18] On November 6, he elected free agency.[19]