Dwelley attended Oak Ridge High School in El Dorado Hills, California, where he played baseball and football.

After moving to tight end, Dwelley made 43 catches for 568 receiving yards and five touchdowns and was named the team's offensive MVP.

[8] He was initially cut at the end of training camp and subsequently signed to the team's practice squad.

[12] Dwelley made his first NFL start during a Week 6 20–7 road victory over the Los Angeles Rams, playing fullback following an injury to starter Kyle Juszczyk.

[13] During a Week 11 36–26 victory over the Arizona Cardinals, Dwelley scored his first NFL touchdown on a four-yard reception from Jimmy Garoppolo.

[15] The 49ers reached Super Bowl LIV, but they lost to the Kansas City Chiefs by a score of 31–20.