As a writer, director, and producer, Reynolds was involved with two highly successful CBS series in the 1970s and early 1980s. Between 1972 and 1983, he produced 121 episodes of M*A*S*H, which he co-created with Larry Gelbart, and for which he also wrote eleven episodes and directed twenty-four. During that same period, he produced twenty episodes of Lou Grant, for which he wrote (or co-wrote) four episodes and directed eleven.
Reynolds was married to actress-turned author Bonnie Jones, who appeared in five episodes of M*A*S*H as Lt. Barbara Bannerman, from 1967 until 1976, when the couple divorced. He and his current wife, actress Ann Sweeny, who also appeared on M*A*S*H as Nurse Carrie Donovan in two episodes, married in 1979 and have one son, Andrew "Buzzy" Reynolds, a semi-professional figure skater.