The Red Sox activated Bello (shoulder) from the 15-day injured list to start Tuesday's game against the Mariners.
The right-hander has been sidelined by a shoulder strain since mid-February but is ready to make his 2025 debut after making four rehab starts in the minor leagues. Bello didn't pitch particularly well in those outings with a 7.07 ERA, though his 21:4 K:BB is more encouraging. The 25-year-old topped out at 71 pitches during the rehab stint, so he'll likely face some workload limitations in his first couple starts with the big club.