Ingels was born Martin Ingerman to a Jewish family in 1936 in the Brooklyn borough of New York City, the son of Jacob and Minnie (née Crown) Ingerman. His uncle was Abraham Beame, the mayor of New York City from 1974 to 1977.

Ingels was married twice: first to Jean Marie Frassinelli in 1960 (they divorced in 1969 after nine years of marriage); later to singer and actress Shirley Jones on November 13, 1977. Despite some drastically different personalities and several separations (Shirley filed, then withdrew, and later had a divorce petition in 2002), the couple remained married until his death in 2015.

He guest-starred on the CBS sitcoms Pete and Gladys, The Ann Sothern Show, and Hennesey. He also appeared in one episode of ABC’s Bewitched as “Diaper Dan”, who plants a microphone bug in Tabitha’s rattle so a competing advertising agency can scoop and steal Darrin’s ideas. He appeared twice as Sol Pomeroy, a United States Army buddy of the character Rob Petrie, on CBS’s The Dick Van Dyke Show. In 1978, Ingels guest starred in Season Two, Episode One of The Love Boat.

In 1993, Ingels sued actress June Allyson for his agency commission. Allyson had appeared in commercials for Depend, and Ingels alleged he was not paid his proper commission as her agent. Allyson denied wrongdoing and countersued. Ingels pleaded no contest to making harassing phone calls to Allyson.

In 2003, he sued radio personality Tom Leykis and Westwood One, saying that comments made about him constituted age discrimination. Ingels had called into Leykis’s radio program objecting to the content, and Leykis declared on the air that Ingels was “not just older than my demographic, you’re the grandfather of my demographic.” In June 2005, Ingels’s lawsuit was dismissed and Ingels was ordered to pay Leykis’s $25,000 in legal fees.

Ingels died from a massive stroke at Tarzana Medical Center in Tarzana, California, on October 21, 2015, at the age of 79. He was survived by his wife, Shirley Jones, and his stepsons. After Ingels’ death, Jones stated “He often drove me crazy, but there’s not a day I won’t miss him and love him to my core.”