The Rain Man legend was the subject of a Life in Pictures retrospective in London, and he became teary as he recalled struggling through his own marriage breakdown while considering a role in the 1979 divorce drama Kramer vs. Kramer.
He told the audience, "I was getting divorced (from first wife Anne Byrne), I'd been partying with drugs and it depleted me in every way."
Hoffman almost refused to meet producer Stanley Jaffe and director/writer Bob Benton because he didn't like the script - and he only joined the cast after it was rewritten.
He adds, "We finished and I got offered a writing credit and stupidly turned it down, but it was a liberating experience for me to push all the stuff I was going through out there."
The 75 year old was moved to tears once again when he later began discussing the movie's child star Justin Henry, who landed the part with no acting experience.
Hoffman explains, "I later discovered he was coming from a home that was breaking up. There was a moment during a break in the testing when I thought, this is the right kid, he's my son."
However, the mood of the evening lightened as Hoffman spoke about his 1982 cross-dressing comedy Tootsie, in which he played an unemployed actor who auditions as a woman to land a role in a soap opera.
Hoffman recalled meeting Jon Voight in a restaurant and tricking his Midnight Cowboy co-star while he was in character: "I went over to him as Dorothy and had an entire conversation about how much I liked his work and managed to fool him."
Previous honourees of the BAFTA Life In Pictures event include Will Ferrell, Kenneth Branagh, Charlize Theron and Colin Firth.