Meeks, a fifth-round pick this season, played in the first six games before suffering an ankle injury. He was placed on injured reserve with a designation to return and resumed practicing two weeks ago. Tuesday was the deadline for the Bills to activate him to their 53-man roster.
The rookie becomes the sixth safety on the Bills' active roster and figures to return to a role on special teams in the final three games.
Westerman, a fourth-year veteran, played in the first 12 games of the season, mostly on special teams. He was inactive last week as the Bills decided to take a closer look at rookie linebacker Ty Powell.
Meanwhile, the Bills swapped wide receivers on their practice squad Tuesday. They re-signed 6-foot-5 rookie Brandon Kaufman, who had been with the team in the preseason, and released Tommy Streeter.