Daniels played for the Washington Huskies from 2013 to 2016. He played in 11 games in 2013, recording 2 solo tackles and 1 tackle assist. He converted from wide receiver to tight end midway through the year. Daniels played in 11 games, starting 4, in 2014, catching 11 passes for 171 yards and 1 touchdown. He also totaled four solo tackles. He played in 13 games, starting 8, in 2015, catching 19 passes for 250 yards and 1 touchdown. Daniels also recorded four solo tackles and two tackle assists. He played in 14 games, starting 6, in 2016, catching 17 passes for 307 yards and 4 touchdowns. He earned Honorable Mention All-Pac-12 honors in 2016. He played in 49 games, starting 18, during his college career, catching 47 passes for 728 yards and 5 touchdowns. Daniels also recorded 10 solo tackles and 3 tackle assists.
Professional career
Daniels was rated the 25th best tight end in the 2017 NFL Draft by NFLDraftScout.com. Lance Zierlein of NFL.com predicted that he would be drafted in the seventh round or be a priority free agent, stating that "Daniels' combination of athletic ability and physical traits figures to land him as a third-day draft pick, but he will have to learn to run routes more effectively as a matchup tight end in the NFL or he will find himself stuck on the practice squad for a couple of seasons."
Indianapolis Colts
Daniels signed with the Indianapolis Colts as an undrafted free agent on May 4, 2017. During the Week 3 31–28 victory against the Cleveland Browns, he recorded his first career NFL reception, which was a six-yarder.
On September 1, 2018, Daniels was traded to the Seattle Seahawks for wide receiver Marcus Johnson. He was waived by the Seahawks on September 25, 2018 and was re-signed to the practice squad. He was promoted to the active roster on October 3, 2018 following an injury to Will Dissly. He was waived on November 24, 2018.
Arizona Cardinals
On November 26, 2018, Daniels was claimed off waivers by the Arizona Cardinals. On August 31, 2019, Daniels was waived by the Cardinals and was signed to the practice squad the next day. He was promoted to the active roster on September 7, 2019, only to be waived two days later and re-signed back to the practice squad. He was promoted back to the active roster on September 21, 2019. He was waived again on September 28, 2019 and re-signed to the practice squad. He was promoted again on October 5. In Week 14 against the Pittsburgh Steelers, Daniels forced a fumble on punter Jordan Berry during a fake punt attempt which was recovered by teammate Dennis Gardeck in the 23–17 loss. He was placed on injured reserve on December 28, 2019.