Financial terms of the deal were not disclosed.
The stations include Bell's KooL FM 101, an adult contemporary station in Calgary, and FAB 94.3, a classic pop station in Winnipeg.
Pattison will also acquire Astral's QX 104 country station in Winnipeg.
The deal is subject to approval by the CRTC and contingent on approval of Bell's acquisition of Astral.
Astral and Bell are selling the stations to comply with the Canadian Radio-television and Telecommunications Commission rules that limit the number of stations a company can own in a single market.
The CRTC wrapped up a week of public hearings last week into Bell's plan to buy Astral.
The federal broadcast regulator killed the deal last year, but the companies revised the plan and sought a fresh review.
Jim Pattison Broadcast Group currently operates 30 FM radio stations as well as three conventional television stations in British Columbia and Alberta.