Pocock scored twice off the back of the rolling maul and flyhalf Christian Lealiifano also crossed before halftime with prop Allan Alaalatoa securing the crucial bonus point with the fourth try around the hour mark.
Another catch-and-drive from a lineout in the 66th minute gave Pocock his second hat-trick of the season to put a gloss on a hardfought victory.
“It was really tough conditions out there,” Brumbies skipper Stephen Moore said in a pitchside interview.
“I knew we had to get the five points and I'm really happy with that.”
The win sent the twice champions clear of New South Wales Waratahs at the top of the Australian conference pending the reigning champions' match against the Cheetahs in South Africa on Saturday.
Taking the national conference title would secure a top-three finish and potentially a bye through the first week of the playoffs before a home semi-final.
Western Force, who got consolation tries from prop Tetera Faulkner and winger Luke Morahan in the last 10 minutes, have long been out of the reckoning for post-season play after a miserable season in which they have managed only two wins.
The rolling maul, with Pocock tucked in with the ball at the back, has been used to great effect by the Canberra-based Brumbies all season and the Force had no answer to it in the 10th and 28th minutes.
Lealiifano's 17th minute effort and his conversion of the first three tries ensured the visitors turned around 21-6 ahead but they had to wait until the 59th minute before Alaalatoa crashed over under the posts to secure post-season play.
Original source: Brumbies seal playoff spot with victory