The Jackson Brodie private investigator series is based on the novels of Kate Atkinson.
Earlier this year, the drama pulled in strong figures for the broadcaster, averaging 5.3 million for its six-episode run in June.
The first of the two new films will be based on Atkinson's Started Early, Took My Dog novel from 2010, reports Broadcast.
"It's incredibly exciting to have Jason Issacs back as the complex and compulsive Jackson Brodie," said BBC executive producer Matthew Read.
"The next series will continue to reflect modern Edinburgh on screen and turn what audiences love most about Kate Atkinson's novels into feature length crime stories that shine a light on dysfunctional families."
Isaacs told Digital Spy in July that the BBC was "on the fence" about doing more Case Histories and that fans should demand more episodes on social networking sites.
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Watch Jason Isaacs and Kate Atkinson discussing the show in an exclusive short video below: