The Easy Rider star wed Margaret 'Parky' DeVogelaere yesterday in Hawaii, according to People.
Fonda has previously been married to Susan Brewer in 1961 and Portia Crockett in 1975.
The 71-year-old actor was most recently seen in CSI: NY, in which he played William Hunt, the ex-partner of Detective Mack Taylor (Gary Sinise).
He has also starred in films such as 3:10 to Yuma, Wild Hogs and Dirty Mary, Crazy Larry.
In January, Fonda found a dead body inside a car in Los Angeles, noticing an apparently unresponsive man while on Sunset Boulevard.