Robbins earned national fame in the 1960s as being the first actor to voice Charlie Brown
On January 20, 2013, Robbins was arrested by San Diego County Sheriff's Department deputies at San Ysidro, California Homeland Security's Port of Entry, while re-entering the United States, and charged with "four felony counts of making a threat to cause death or great bodily injury and one felony count of stalking." The four counts involve four victims, including a San Diego Police sergeant, whom Robbins reportedly threatened with bodily harm during a January 13, 2013 incident. He was held on $550,000 bond. On May 8, 2013, he was sentenced to a year in jail for threatening his former girlfriend and stalking her plastic surgeon, but he was allowed to log time in treatment instead. After release, he was sent to a residential drug treatment center.
In 2015, Robbins was arrested for multiple probation violations, including drinking alcohol and failing to complete mandatory domestic violence classes. On June 5, 2015, he was ordered to undergo a mental health exam after an outburst during a court proceeding in San Diego.
On December 7, 2015, Robbins was sentenced to four years and eight months in prison as part of a plea agreement for sending threatening letters to a manager and his wife of the mobile home park in which he lived in Oceanside, California. Robbins has stated at previous hearings that he suffers from bipolar disorder and paranoid schizophrenia
. Robbins was incarcerated at the California Institution for Men in Chino, California and was transferred to a psychiatric hospital because of his mental state. He was released in 2019 "[a]fter serving 80 percent" of his sentence, under orders not to drink alcohol or take any illegal drugs.