The first Broadway musical for which he wrote the lyrics was the 1963 musical Hot Spot starring Judy Holliday, with music by Mary Rodgers. He contributed lyrics to Vernon Duke’s musical Zenda which ran in California in 1963 but did not reach Broadway. In 1967, he wrote the lyrics for Mata Hari, which was produced by David Merrick. He wrote lyrics to Richard Rodgers’ music and Peter Stone’s book for the musical Two by Two (1970), which starred Danny Kaye and ran on Broadway for 10 months.

In the early 1970s, he worked in television where he conceived, produced, wrote and directed six television variety specials. In 1971, he won the Emmy Award for Annie, The Women in the Life of a Man, which starred Anne Bancroft. In 1972, he won two primetime Emmy Awards for S’Wonderful, S’Marvelous, S’Gershwin, which starred, among others, Jack Lemmon, Fred Astaire, Ethel Merman, Larry Kert, and Robert Guillaume. His other television specials included Get Happy (starring Jack Lemmon, Johnny Mathis, Cass Elliot), Dames at Sea (1971, starring Ann-Margret, Anne Meara, and Ann Miller), Dick Shawn), Harvey Evans), and Fred Gywnne). Cole Porter in Paris (starring Perry Como, Twiggy, Louis Jourdan, Charles Aznavour), and a second Bancroft special, titled Annie and the Hoods. He supplied music and lyrics for the song “The Best Thing You’ve Ever Done”, sung by Barbra Streisand on her multi-platinum album The Way We Were.

He made his Broadway directing debut in 1973, conceiving and directing the revue Nash at Nine, based on the works of Ogden Nash and starring E.G. Marshall and running for 21 performances. He next directed the revue Music! Music!, which had a libretto by Alan Jay Lerner and ran at City Center for 37 performances in 1974. He directed The National Lampoon Show (1975) and its road company. The New York version starred John Belushi, Gilda Radner, Bill Murray, and other Saturday Night Live performers.

He wrote the lyrics for I Remember Mama (1979) with music by Richard Rodgers, and directed, wrote the lyrics for, and co-wrote the book for The First (1981), a musical about Jackie Robinson and the integration of baseball, which he was nominated for two Tony Awards. He directed A Little Family Business on Broadway in 1982, which starred Angela Lansbury and John McMartin, and Eli Wallach and Anne Jackson in The Flowering Peach for Tony Randall’s National Theatre, on Broadway. He wrote additional lyrics for La Strada (1969) and The Madwoman of Central Park West (1979). He directed Cafe Crown in 1988 at the Off-Broadway Public Theater, which subsequently transferred to Broadway in 1989. In 1989 he directed Sid Caesar & Company on Broadway. He directed Laughing Matters in 1989 at the Theater at St. Peter’s Church, New York, a revue written by and starring Peter Tolan and Linda Wallem. He directed Jeanne La Pucelle (1997) in Montreal, with book and lyrics by Vincent de Tourdonnet and music by Peter Sipos.

He conceived and directed the cabaret revue Upstairs at O’Neals, which ran Off-Broadway from October 1982 to July 1983 at O’Neal’s restaurant. He directed and wrote the book with Douglas Bernstein and Denis Markell and music with Marvin Hamlisch, Thomas Meehan, Billy Weeden and David Finkle for The No Frills Revue; sketches were written by Ronny Graham among others. The revue featured his daughter, Sasha Charnin Morrison. The revue opened Off-Broadway at the Cherry Lane Theater in October 1987. He directed the premiere stage adaptation of Jules Feiffer’s Carnal Knowledge Off-Broadway at the Kaufman Theatre in 1990 and Wallach and Jackson in In Persons.

In the 1990s, he directed dozens of companies of Annie, and its sequel Annie Warbucks; in 1997, he directed three additional companies of Annie in London, Australia and Amsterdam. He directed the 20th anniversary production of Annie on Broadway, and in 2004, he directed the 30th anniversary production of Annie, produced by Ken Gentry and Networks. It ran for three and a half years all over the U.S.

In regional theatre, he directed Robin Hood: The Legend Continues which ran at the Village Theatre, Issaquah, Washington in December 2004. He also wrote the lyrics, with music by Peter Sipos and the book by Thomas Meehan, and the cast featured Shelly Burch. He directed A.R. Gurney’s Later Life in Orlando in 2005, featuring Shelly Burch. He created, wrote or directed regional shows including Love is Love, Shadowlands, and in 2010, Sleuth, all for the Village Theatre in Issaquah.

He moved back to the East Coast for the 35th Anniversary revival of Annie, which opened on Broadway at the Palace Theatre in November 2012 and ran until January 2014.

Charnin moved to Issaquah, Washington after directing Robin Hood and stayed there until he returned to New York in 2012. He was Artistic Director of Showtunes!, a theatre company in Seattle, Washington, devoted to resurrecting forgotten and unsung musicals, and celebrating the works of composers, including Richard Rodgers and Irving Berlin, and producing them in concert at Benaroya Hall in Seattle.

He created, produced and directed night club acts for his wife, Shelly Burch. and prepared a new one-woman theatrical entertainment for Shelly Burch for Fall 2014. He directed the revival of Two by Two, starring Jason Alexander as Noah, and Tovah Feldshuh as Noah’s wife. It was performed at the York Theatre in 2014 and a new Broadway production was being planned.

On the East Coast, he created and directed three musicals for the Emelin Theatre in Mamaroneck and in 2014 directed the national tour of Annie for Troika Productions.

He had two children, Randy Charnin and Sasha Charnin Morrison and three step-children Joel, Dayna, and Richard Bennett whom he raised and three grandchildren, Maxwell Charnin and Gus and Oliver Morrison. He lived with his wife, Shelly Burch, in New York. He died at a hospital in White Plains, New York on July 6, 2019, having been hospitalized after suffering a heart attack on July 3.