Martin Charnin created the role of Big Deal in the original Broadway company of West Side Story in 1957, the only acting job he ever had. He began writing during West Side and his first collaborator was Mary Rodgers.

He has subsequently been the director, lyricist, composer, librettist, producer or a combination of the aforementioned, for over 140 theatrical productions, including Annie, Annie Warbucks, the Rock Opera version of Joan of Arc, Mata Hari, Loose Lips, Star-Crossed, Sid Caesar and Company, Carnal Knowledge, In Persons starring Eli Wallach and Anne Jackson, The Flowering Peach, Winchell, the revised Can Can by Cole Porter (for which he wrote a new libretto), Cafe Crown, Mike, Laughing Matters, The No Frills Revue, The First, On the Swing Shift, A Little Family Business, Upstairs at O'Neals, The National Lampoon Show, Lena Horne on Broadway, I Remember Mama, Hot Spot, Zenda, Put It In Writing, Fallout, Kaleidoscope, Ballad For A Firing Squad, La Strada, Nash at Nine, Music Music, Two by Two, And in London, Bar Mitzvah Boy, Bless the Bride, The 9 1/2 Quid Revue, and internationally and regionally, 17 productions of Annie.

In the 60's and 70's he turned to Television and created 7 specials that garnered over 15 Emmy Awards, and the Peabody Award for Broadcasting.

His collaborators have included Peter Allen, Harold Arlen,Vernon Duke, Keith Levenson, Michael Danziker, Peter Sipos, Mary Rodgers, Marvin Hamlisch, Richard Rodgers, and Charles Strouse.

He has written for and directed among others, Fred Astaire, Jack Lemmon, Anne Bancroft, Lena Horne, Danny Kaye, Angela Lansbury, Johnny Mathis, Bill Murray,Jon Stewart, Bebe Neuwirth, Bernadette Peters, Sarah Jessica Parker, Gilda Radner, Molly Ringwald, Chita Rivera, Lou Reed, Susan Sarandon, Tim Robbins, Joan Rivers, Chuck D., Phoebe Snow, Shirley MacLaine, Marlo Thomas, Julianne Moore, Martha Plimpton, and Barbra Streisand.

He is currently reviving Annie Warbucks, and Two by Two, and in 2019, audiences will see his new musical version of Robin Hood, written with Peter Sipos and Thomas Meehan, and later on that year, Wallenberg, written with Laurence Rosenthal, and Felicia Needleman.

Charnin was the artistic director of Seattle's Showtunes for 7 years, before moving back to New York for the 4th incarnation of Annie on Broadway. He is also in the process of creating a one woman theatrical entertainment for his wife, Broadway and television star Shelly Burch.