A graduate of the American Academy of Dramatic Arts, he was discovered in New York by a Universal Studios talent agent while performing the lead in the play Philadelphia, Here I Come.

After signing with Universal and moving back to California, he slowly built up his resume with work on such dramatic series as Adam-12 (1968); Marcus Welby, M.D.

[1] Randolph Mantooth has spoken regularly at Firefighter and EMS conferences and symposia across the United States while maintaining an active acting career.

[11] Mantooth's earlier jobs included work as an elevator operator at the Madison Avenue Baptist Church and as a page at NBC Studios at Rockefeller Center in New York City.

[11] After signing with Universal[15] and moving back to California, he slowly built up his resume with work on such dramatic series as Adam-12 (1968), Marcus Welby, M.D.

[10] Producer Robert A. Cinader saw Randolph Mantooth in a small role on The Bold Ones opposite Hal Holbrook that led to his decision to cast him as paramedic John Gage on Emergency!

Randolph Mantooth and Kevin Tighe were part of a paramedic team assigned to Squad 51 of the Los Angeles County Fire Department.

[11] To train for their parts, the actors, Randolph Mantooth along with Kevin Tighe, "...sat in on paramedic classes" (although they never took any written exams) "and rode out on extensive ride-a-longs with LACoFD".

[1] The show ran six seasons (129 episodes) with seven two-hour television movie specials including the pilot film (The Wedsworth-Townsend Act).

at the Smithsonian, Project 51 was created in an effort to raise funds for a children's burn charity,[8][18] and exhibit the restored squad truck around the country.

Mantooth, along with Marco Lopez, Tim Donnelly, Ron Pinkard and Mike Stoker, embarked on a 10-city tour with the squad to raise funds for charity on their way to Washington, D.C., with their final destination being the Smithsonian.

[2] The honor was bestowed on the men for their contributions to the fire service and emergency medicine through educating and inspiring children and adults to be firefighters, EMTs, or paramedics.

The show was sold overseas and aired in a number of countries, including Germany where it was renamed Notruf California, in addition to being dubbed in Spanish in the United States.

[1] Tighe and Mantooth also presented the work of firefighters and paramedics from the Los Angeles County Fire Department on the NBC Saturday morning children's series Go!.

[1] Mantooth's and Tighe's likenesses were used for games, puzzles, lunch boxes, action figures, and comic books connected to the series.

[1] Mantooth and Kevin Tighe's characters John Gage and Roy DeSoto appeared on another Robert A. Cinader created series, Sierra.

[23] While talking with Tom Blixa of WTVN, Mantooth said that at first it was a little intimidating working with Robert Fuller, Bobby Troup and Julie London, because they were all big stars, but after doing a series with them for seven years they all became like family.

[17] In the same interview, while discussing happenings behind the scenes and blooper reels, Mantooth said there was "a lot of salty language though"..."and we learned every bad word from Julie London"...”I love her to death but she herself said 'I'm a broad'".

"[20] In addition to Mantooth working as an actor for over forty years, he has remained an advocate of firefighters, paramedics, EMTs, and other emergency medical services providers.

He does speeches and personal appearances each year at events across the country,[15] discussing the "inside story of the development of the television series Emergency!

[24] Having worked closely with the nation's first certified firefighter/paramedics, who served as technical advisors on the set of Emergency!, Mantooth brings a perspective and insight into the startup and history of pre-hospital treatment in the field.

[3] Mantooth serves as honorary chairman and spokesperson for the non-profit County of Los Angeles Fire Museum Association.

In May 2012, he filmed an Emergency Preparedness video with Monte Fronk in Minnesota at the Mille Lacs Ojibwe Reservation to be distributed to tribal leaders.

Mantooth also made guest appearances on series such as China Beach, MacGyver, Baywatch, Diagnosis: Murder, JAG, Promised Land and Walker, Texas Ranger during the 1990s.

Feature film roles include Admiral Edwards in Agent Red (2000), Dr. Willis in He Was a Quiet Man (2007), Ambassador Cartwright in Scream of the Bikini (2009), Richard Cranehill in Bold Native (2010), and Detective Bodrogi in Killer Holiday (2013).

Mantooth also starred on series such as ER, Criminal Minds, Ghost Whisperer, and most recently as Charlie Horse in Sons of Anarchy in 2011.

[15] Since 2012, the actor has represented the Seminole Nation on the American Indian Advisory Board at the San Diego International Film Festival.

[18] In 1984, Mantooth worked with David Carradine and Will Sampson, along with Native actors, in a production of Black Elk Speaks for the American Indian Theatre Company in Tulsa, Oklahoma.

[7][36] Mantooth has also performed in three works written by William S. Yellow Robe, Jr.: The Pendleton Blanket, Wink-Dah and The Independence of Eddie Rose.

Mantooth is an Associate Artist of The Purple Rose Theatre Company in Chelsea, Michigan, founded by Jeff Daniels,[5] since 2003.