Blake began his career in the "Our Gang" comedy shorts, billed as Mickey Gubistosi. He was rechristened as Bobby Blake at MGM, where he appeared as a juvenile in small roles in such films as "I Love You Again" (1940) , "Andy Hardy's Double Life" (1942) and "Salute to the Marines" (1943). While he never reached child stardom, he earned some notice, billed as Robby Blake, portraying "Little Beaver" in a string of Republic low-budget Westerns while in his early teens. He continued making appearances as either 'Bobby' or 'Robby' Blake into the 50s, often in small roles. Yet, in 1950, he co-produced and starred in (as Robert Blake) the independently made "Blackout". Later, he worked as a stuntman and actor in two Columbia feature films. By the early 60s, he was almost always in supporting parts (e.g., as one of the rapist GIs in "Town Without Pity" (1961) and as a member of JFK's crew in "P.T. 109" (1963). It was not until "In Cold Blood" that Blake was able to demonstrate his acting mettle. Cast as murderer Perry Smith, the film and Blake's performance earned raves. He then played the title role in "Tell Them Willie Boy Is Here" (1969) before slipping into weak productions.

Blake worked sporadically in TV during the 1950s and 60s, beginning with an episode of "Fireside Theatre" in 1949, and as a member of the anthology players on "The Richard Boone Show" from 1963-64. But he did not get his big break until 1975. ABC had cast Tony Musante as "Toma", a big city yet unconventional cop. When Musante elected to bow out of the series, ABC sought a replacement. With Blake, the network decided not to re-cast Musante, but instead revamp the series completely. The result was a popular, gritty weekly hour in which Blake's character lived in a seedy hotel and used au courant street jargon. Blake won an Emmy for his work and became a TV star. He followed "Baretta" with a series of TV-movies as a detective named "Joe Dancer", but NBC declined to turn the movies into a regular series (Blake was also executive producer). Yet, Blake was proving his abilities as a dramatic actor, executive producing and starring as George in the NBC remake of "Of Mice and Men" (1981), and as Jimmy Hoffa in the 1983 syndicated miniseries "Blood Ties". This lead to another series, the short-lived "Hell Town" (NBC, 1985), in which Blake was a crusading neighborhood priest. Yet, Blake seemed to want to destroy his career as much as build it, and word spread in Hollywood about his fits, self-destructive behavior and possible substance abuse. With the demise of "Hell Town", Blake practically disappeared from Hollywood.

But his career was not over. Blake re-emerged in 1993 as the star of the CBS TV-movie, "Judgment Day: The John List Story", based on the true story of an accountant who murdered his family and got away with the deed for almost two decades. In 1995, he returned to the big screen in a strong supporting role in "Money Train" and subsequently delivered a suitably creepy turn as a mysterious man in David Lynch's "Lost Highway" (1997).

"Lost Highway" would be Robert Blake's last film appearance before the startling events of May 4, 2001, when his wife Bonny Lee Bakely-whom he had married only a few months earlier-was found dead of a gunshot wound in Blake's car while the actor was allegedly a block away looking for a lost firearm in the Studio City restaurant they had just dined in. As police investigated, Blake became a principal in a sordid story: according to the actor's attorney, Bakely was a celebrity-obsessed gold-digger who had previously pursued the likes of Marlon Brando's son Christian and musician Jerry Lee Lewis; Blake married her after she became pregnant with their daughter, Rosie, and DNA tests proved he was the father. Blake's camp also contended, with supporting evidence, that Bakely was a career mail-order scam artist who bilked aged and lonely men out their money with promises of marriage, sex and nude photos, and a woman who had more than her share of enemies-all of which were potential suspects in her murder. Nevertheless, nearly a year later, on April 22, 2002, Los Angeles police arrested and charged Blake with Bakely's slaying, along with his longtime bodyguard, Earl Caldwell. Blake paid Caldwell's bail, but the courts denied bail to the actor himself, leaving him incarcerated for several months before his trial went to court. Blake issued a series of protestations of innocence from his cell, including a compelling sit-down with journalist Barbara Walters in which he vehemently denied having a role in Bakely's murder--His compulsion for media attention that would ultimately cause his high-profile attorney Harlan Braun to quit the case. Once the trial was underway, the actor took a more understated approach to his publicity, and in a revelation that surprised many, the prosecution's case failed to sway the jury and Blake--whose interview with Walters was shown to the jury in lieu of having the actor risk taking the stand--was aquitted of the crime in March 2005. He immediately consented to an interview with Walters, speculating that his wife was killed by “somebody whose father was taken for a ride" as a result of Bakely's alleged scams, and he credited the first Walters interview for clearing his name. However, despite his victory in criminal court, in November 2005 a civil court jury found Blake liable in the death of his wife, Bonny Lee Bakley and ordered him to pay her family damages in the amount of $30 million.