The ranch-style house was designed by Cliff May in 1953 as his personal residence. It was an experiment in open plan living, with walls enclosing only the bathrooms and long drapes and rolling cabinets defining other rooms.
O'Neill, 65, has played patriarch Jay Pritchett on the sitcom since 2009. He also is known for his starring role on "Married With Children" (1987-97).
Richardson, 55, won Oscars for "JFK" (1991) and "The Aviator" (2004). His credits include "Shutter Island" (2010) and "Inglourious Basterds" (2009).
The property had been listed at $3,495,000.
Barry Sloane of Sotheby's International Realty, Beverly Hills, was the listing agent. Nancie Richards and Dawn Robertson of the Brokerage Beverly Hills represented O'Neill.