Born April 23, 1991, in Medina, Ohio, Kyle Juszczyk attended Cloverleaf High School in Lodi, where he played tight end and won the Suburban League shot put championship in track and field. Harvard University recruited him to play tight end for the Crimson under coach Tim Murphy from 2009 to 2012. Juszczyk finished his collegiate career with 125 receptions for 1,576 yards and 22 touchdowns, earning unanimous first-team All-Ivy League honors as a senior.

The Baltimore Ravens selected Juszczyk in the fourth round (130th overall) of the 2013 NFL draft, making him the first fullback ever drafted from Harvard and only the tenth player in school history selected. After serving as Vonta Leach's backup his rookie season, Juszczyk became the Ravens' starting fullback in 2014 and earned his first Pro Bowl selection in 2016, playing more snaps than any other fullback in the league that season.

Juszczyk entered free agency in 2017 as the top fullback on the market. On March 9, 2017, the San Francisco 49ers signed him to a four-year, $21 million contract—the largest ever for a fullback in NFL history. Head coach Kyle Shanahan transformed Juszczyk into an "offensive weapon," utilizing his versatility at fullback, tight end, running back, and wide receiver. His elite blocking opened lanes for the 49ers' dominant rushing attack while his receiving skills created mismatches in the passing game. Super Bowl LIV showcased his dual-threat ability when he caught three passes for 39 yards and a touchdown against Kansas City, becoming the first Harvard alumnus to score a touchdown in Super Bowl history. Week 16 of the 2020 season against Arizona featured his exceptional versatility as he caught two receiving touchdowns in the 20-12 victory. His most memorable moment came in Super Bowl LVIII when his spectacular hurdle on the opening drive ignited the crowd at Allegiant Stadium.

Through 13 NFL seasons, Juszczyk has compiled 305 receptions for 2,877 yards and 20 receiving touchdowns along with 234 rushing yards and six rushing touchdowns. His record ten consecutive Pro Bowl selections (2016-2025) represent the most by any fullback in NFL history, and he earned first-team All-Pro honors in 2023 and 2025 while leading NFL fullbacks in receiving yards during the 2025 season.

Juszczyk married American fashion designer Kristin Arceri in July 2019. During the 2023 season, Kristin gained national attention after designing a custom Travis Kelce-inspired jacket for Taylor Swift, showcasing her creative talents that later earned her a licensing deal with the NFL to design and sell custom apparel. The couple resides in the Bay Area where Juszczyk continues his career with the 49ers.