The Cleveland Browns selected Callaway in the fourth round (105th overall) of the 2018 NFL Draft. The Browns traded their fourth and sixth round picks to the New England Patriots and received the their fourth round pick in exchange in order to draft Callaway.
He made his professional regular season debut in the Cleveland Browns’ season-opener against the Pittsburgh Steelers and returned a kick for an eight-yard gain during their 21–21 tie. On September 16, 2018, Callaway earned his first career start and replaced Josh Gordon due to a hamstring injury. He recorded three receptions for 81-yards and scored his first career touchdown during a 21–18 loss at the New Orleans Saints in Week 2. Callaway caught his first career touchdown reception on a 47-yard pass by Browns’ quarterback Tyrod Taylor during the fourth quarter. The following day, head coach Hue Jackson named Callaway the starting wide receiver after the Browns traded Josh Gordon to the New England Patriots. In Week 8, Callaway made a season-high five receptions for 36-yards and caught a one-yard touchdown pass thrown by Baker Mayfield as the Browns lost 33–18 at the Pittsburgh Steelers.
On August 9, 2019, Callaway was suspended for the first four games of the 2019 season for violating the NFL’s substance abuse policy. He was reinstated from suspension on September 30, and was activated prior to Week 5. On November 14, the Browns waived Callaway after showing up late to meetings and practices. He was also facing a 10-game suspension at the time of his release. He lost his appeal on November 15, and was suspended for the final seven weeks of the 2019 regular season and the first three weeks of the 2020 regular season.
During his time with the Browns Callaway has racked up 675 receiving yards, totaling for five touchdowns. This is a huge pickup for the Vipers to say the least. Callaway has had a rocky past, but looks to re-focus on his career with the XFL.