Castillo (shoulder) will be activated from the 10-day injured list to start Monday against the Brewers, Mark Sheldon of MLB.com reports.
The 29-year-old made his final rehab start with Triple-A Louisville on Wednesday, and he'll remain on a five-day pitching schedule while coming off the injured list. Castillo threw 76 pitches across 4.1 frames in that outing, so any workload limitations should be minor despite it being his first start of 2022.