The Tampa Bay Vipers announced the signing of Callaway, who was a fourth-round pick in the 2018 NFL Draft, on Thursday.
After a solid rookie season with the Browns in which Callaway had 43 catches for 586 yards and five touchdowns, the wideout was suspended for the first four games of the 2019 campaign due to a violation of the league's substance abuse policy.
The 23-year-old appeared in four NFL contests after being reinstated but was later released amid a potential 10-game ban for using a tainted CBD product.
Callaway also wore out his welcome in Cleveland with his tardiness, which included arriving late to a game against the Buffalo Bills.
The second incarnation of the XFL is expected to exclude cannabis in its drug-testing protocols.