He played college football for the Harvard Crimson, and was selected by the Baltimore Ravens in the fourth round of the 2013 NFL draft.

[2] In addition to his primary position of fullback, Juszczyk has also situationally played tight end, running back, and wide receiver, with 49ers head coach Kyle Shanahan once describing Juszczyk's role in the 49ers' offense as an "offensive weapon".

[5] Juszczyk attended Harvard University, where he played tight end for the Crimson under coach Tim Murphy.

[8] Coming out of Harvard, many analysts and scouts projected Juszczyk to be a third or fourth round pick.

Although he was not invited to the NFL Combine, Juszczyk performed all the required drills and positional workouts at Harvard's Pro Day.

[13] Juszczyk entered training camp his rookie year competing with veteran Vonta Leach to be the Raven's starting fullback.

[14] He made his professional regular season debut in the Ravens' season-opening 49–27 loss to the Denver Broncos.

[16] The following year, Juszczyk became the Ravens' starting fullback with the release of Vonta Leach in February.

[19] In a Week 10 matchup against the Tennessee Titans, Juszczyk caught a season-high three passes for 26 receiving yards during a 21–7 victory.

Juszczyk returned as the starting fullback in 2015 after winning the job over Kiero Small in training camp.

[26] On December 27, 2015, Juszczyk caught five passes for a season-high 55 receiving yards as the Ravens defeated the Pittsburgh Steelers 20–17.

[31] On October 2, 2016, Juszczyk caught a career-high six passes for 56 receiving yards as the Ravens lost to the Oakland Raiders 28–27.

[36] Juszczyk entered free agency for the first time in his career in 2017 and was the top fullback on the market.

He received interest and offers from multiple teams, including the Philadelphia Eagles, Browns, Bills, and the San Francisco 49ers.

The Eagles were the top team to possibly land the prized free agent at first, but the Bills overtook them as the favorite, as they were looking for a stable replacement for Jerome Felton.

[43] During Week 3 against the Kansas City Chiefs, he scored his first touchdown of the season on a 35-yard pass from Jimmy Garoppolo.

[67] During the 2023 season, Kristin gained national attention after designing a Travis Kelce-inspired jacket for Taylor Swift; she would later obtain a licensing deal with the NFL.