As a true freshman at Notre Dame in 2017, Kmet played in all 13 games and had two receptions for 14 yards. As a sophomore in 2018, he played in 11 games and had 15 receptions for 162 yards. Kmet took over as the starting tight end his junior year in 2019.[5] He missed the first three games of the season due to a broken collarbone.[6] In November, he announced that he would return to Notre Dame for his senior season rather than enter the 2020 NFL draft.[7][8]
On January 2, 2020, Kmet announced he would forgo his senior season at Notre Dame and would enter the 2020 NFL Draft.[9]
Kmet also played baseball at Notre Dame.[10] As a freshman in 2018, Kmet appeared in 26 games as a relief pitcher and made one start. He finished the season 2–5 with a 5.05 earned run average (ERA), 39 strikeouts and a team-leading eight saves.[11] As a sophomore in 2019, Kmet appeared in eight games with one start, before suffering an arm injury.[12] He finished the season 0–2 with a 2.89 ERA and 27 strikeouts.
Considered a top tight end prospect for the 2020 NFL Draft, CBS Sports ranked him as the best tight end in the draft, while Pro Football Focus ranked him as the second-best. He was projected as a second-round pick.[15][16]
2020 season
The Chicago Bears selected him in the second round with the 43rd overall pick, which was previously acquired from the Las Vegas Raiders along with Khalil Mack as part of the trade that sent two first-round picks (Josh Jacobs and Damon Arnette) to the Raiders.[17] He signed a four-year rookie contract with the team on July 21.[18]
Kmet began his rookie season primarily as a blocker.[19] In Week 2 against the New York Giants, he recorded his first NFL reception with a 12-yard catch,[20] followed by his first touchdown four games later against the Carolina Panthers on a nine-yard score in the 23–16 victory.[21]
2021 season
Kmet appeared in all 17 games for the Bears and caught 60 passes for 612 yards during the 2021 season.[22]
2022 season
Bears offensive coordinatorLuke Getsy was optimistic about Kmet, who did not catch a touchdown pass in 2021. He commented on Kmet's versatility stating, "You talk about a guy that we hope can do a lot of different things. We’ve lined him up wide. We've let him do some routes outside. We've brought him in tight. We've put him in line and made him block the big boys up front too and I think the cool part about him is that he can do all of that stuff really well."[23] During the 2022 season, Kmet recorded 50 receptions for 544 yards and seven touchdowns.[24] He led the Bears in receptions, receiving touchdowns, and receiving yards.[25]
2023 season
On July 26, 2023, Kmet signed a four-year, $50 million contract extension with the Bears.[26][27] He appeared in all 17 games for the Bears and finished the season with 73 receptions for 719 yards and six touchdowns.[28]
2024 season
On October 13, 2024 against the Jacksonville Jaguars, Kmet had 5 receptions for 70 yards and 2 touchdowns. In the same game, Kmet also snapped six long snaps as the emergency long snapper after starter Scott Daly suffered a knee injury, uniquely earning him NFC Special Teams Player of the Week.[29][30]