According to the report, Sampson will compete for a bullpen spot with the D-backs in Spring Training.
The 25-year-old was non-tendered by the Reds earlier in December and became a free agent.
In 18 appearances for the Reds last season, including two starts, Sampson posted a 4.35 ERA with 27 walks and 42 strikeouts in 39 1/3 innings. He fared better in 18 outings in Triple-A, nine of which were starts. He had a 1.88 ERA, 21 walks and 62 strikeouts in 62 1/3 innings.
Sampson was a fourth-round pick by the Padres in the 2009 Draft who was selected off waivers by the Reds in January 2015.