Jackson was born in Wendell in Gooding County in southern Idaho to Maurita (or Maurite ) Kathleen Gilbert and Curtis Loys Jackson, Sr. Her mother provided drama, singing, and dancing lessons for Sherry and her two brothers, Curtis L. Jackson, Jr., and Gary L. Jackson, beginning in their formative years. After her husband died in 1948, Maurita moved the family from Wendell to Los Angeles, California.

By one account Maurita, who had been told while still in Idaho that her children should be in films, was referred to a theatrical agent by a tour bus driver whom they met in Los Angeles. According to another, she was referred by the friend of an agent who saw Sherry eating ice cream on the Sunset Strip. Apocryphal perhaps, but within the year Sherry had her first screen test, for The Snake Pit with Olivia De Havilland, and by the age of seven appeared in her first feature film, the 1949 musical You're My Everything, which starred Anne Baxter and Dan Dailey.

During the course of appearing in several of the Ma and Pa Kettle movies during the 1950s as Susie Kettle, one of the titular couple's numerous children, she also appeared in The Breaking Point, which starred John Garfield in the actor's penultimate film role. In 1952, she portrayed the emotionally volatile visionary and ascetic Jacinta Marto in The Miracle of Our Lady of Fatima, and the following year played John Wayne's daughter in the football-themed Trouble Along the Way.

In 1950, young Sherry became friends with actor Steve Cochran while working with him on The Lion and the Horse. Steve introduced his friend, Writer Montgomery Pittman, to Sherry's widowed mother. A romance developed, and Pittman married Maurita Jackson in a small ceremony on June 4, 1952, in Torrance, California, with Sherry as flower girl and younger brother Gary as ring-bearer; Cochran himself was Pittman's best man. In 1955 Cochran hired Pittman to write his next film, Come Next Spring, the first that Cochran produced himself. Sherry played the part of Cochran's mute daughter Annie Ballot, a role Pittman wrote specifically for his step-daughter.

Jackson may be best remembered for her role as older daughter Terry Williams on The Danny Thomas Show (known as Make Room for Daddy during the first three seasons) from 1953–1958. During the course of her five years on the series, she established a strong bond with her on-screen mother, Jean Hagen, but Hagen left the series after the third season in 1956.

Worn out from the relentless pace of the program, Jackson left the program once her five-year contract ended two years later. Jackson received a star at 6324 Hollywood Blvd. on the Hollywood Walk of Fame on February 8, 1960 for her work in television. Penny Parker replaced her in the 1959-60 season, but the character was written out of the series after Parker married.

Over the next few years, Jackson broadened her range of acting roles, appearing as a hit woman on 77 Sunset Strip, a freed Apache captive who yearns to return to the reservation on The Tall Man, an alcoholic on Mr. Novak, a woman accused of murder on Perry Mason, and an unstable mother-to-be on Wagon Train. After a 1965 appearance on Gomer Pyle, U.S.M.C., she then made guest appearances on Lost in Space ("The Space Croppers" (1966 March 30)) reuniting her with Angela Cartwright, My Three Sons, The Wild Wild West ("The Night of the Vicious Valentine" and "The Night of the Gruesome Games", as two different characters), Batman, and the original Star Trek series. On the latter program, she made one of her more memorable portrayals as the android Andrea in the episode "What Are Little Girls Made Of?".

In 1966, Jackson was cast as Katherine "Kate" Turner, a young woman from Boston who takes over a wagon train after the death of the trailmaster, in the episode "Lady of the Plains" of the syndicated series Death Valley Days. DeForest Kelley plays a gambler, Elliott Webster, who falls in love with her though she is engaged to marry once the wagon train reaches Salt Lake City.

When Blake Edwards remade the television series Peter Gunn as a feature film entitled Gunn (1967), Jackson was filmed in a nude scene that appeared only in the international version, not the U.S. release. Stills of the nude scene appeared in the August 1967 issue of Playboy magazine, in a pictorial entitled "Make Room For Sherry". The movie has not yet been released on VHS or DVD.

In 1967, Jackson began a five-year relationship with Business executive and horse breeder, Fletcher R. Jones, a union that ended on November 7, 1972, when Jones was killed in a plane crash eight miles east of Santa Ynez Airport in Santa Barbara County, California. Five months after Jones' death, Jackson filed suit against his estate, asking for more than $1 million, with her attorneys stating that Jones had promised to provide her with at least $25,000 a year for the rest of her life. The litigation proved unsuccessful.