He died at his home in Los Angeles on Christmas Eve surrounded by his family.
His TV credits include Auf Weidersen Pet, Shine on Harvey Moon, Lovejoy and Birds of a Feather, as well as Girls on Top, which also starred Ullman.
Born in Ealing on May 21, 1946, McKeown left school at age 14 to become a hairdresser and worked with clients such as The Beatles, Elizabeth Taylor, Richard Burton and Michael Caine.
He also created hairstyles for iconic 1960s films such as If and Get Carter, before moving into the world of advertising.
He went on to found production company Witzend with comedy writers Dick Clement and Ian La Frenais, establishing himself him as one of the first independent television producers in the UK.
As co-creators of Tracey Takes On… and State of the Union with his wife, McKeown and Ullman won an Emmy for outstanding variety, musical or comedy series in 1997.
Later in his career, he worked on stage productions and produced Lennon The Musical on Broadway, with Yoko Ono, and the stage and TV versions of Jerry Springer: The Opera.
He and Ullman, with whom he has two children, moved to the US in 1996.
Writing on Twitter, McKeown's daughter Mabel paid tribute to her father: "My brilliant, funny, extraordinary father Allan McKeown passed away on Christmas Eve. Thank you all for the love."