Born in Pittsburgh, Pennsylvania, Johnson is of African American and Puerto Rican descent. Johnson's beginnings in show Business are attributed to her uncle, David W. Duclon, a successful Screenwriter and TV Producer who, early on, was known for his work on Happy Days in the 1970s. Duclon encouraged his niece's Desire to act, and secured her an audition. In 1984, after two seasons as executive Producer of NBC's Silver Spoons, Duclon successfully pitched a new pilot to the network about an orphaned young girl who is taken in by a curmudgeonly older man. The concept won the approval of NBC programming chief Brandon Tartikoff, who named the titular character, and series, Punky Brewster (after a girl he had known in his youth). Johnson was cast by NBC in the role of Punky's (Soleil Moon Frye) best friend, the character of which was modeled and named after herself. Punky Brewster was an immediate success among young audiences, and Johnson continued as the fictional Cherie throughout the series' run (1984–86 on NBC, and 1987–88 in first-run syndication).

In 1990, Johnson began playing Maxine "Max" Johnson, the best friend of Laura Winslow (Kellie Shanygne Williams) on Family Matters, appearing in the recurring role until the series' end in 1998. Duclon was again her employer, as he served as one of the executive producers of Family Matters during Johnson's run on the show. In addition to her starring roles, Johnson has made guest appearances on The Parkers, and performed a vocal guest role on The Proud Family. She has also appeared on Days of Our Lives. In the early 2000s, Johnson began producing films. In 2009, she wrote, starred and produced the film I Do... I Did!. In 2010, she starred in the films Lights Out, Nobody Smiling and Guardian of Eden. She then signed on to appear in the romantic film Fanaddict, which was shot in 2011 and is slated for release later in 2013.

In 2009, she wrote, starred and produced the independent film I Do... I Did!, playing Vivian. Johnson has so far produced eight films. In 2010, she made Writer debut when she released her book Around The World Twice. In 2011, she released her second, writing Two Different Walks Of Life A Celebrity and Average Housewife. Her third novel Peaches & Cream is available. Her book Stupid Guys Diary was released in August 2013.

Her first novel, Around The World Twice, was released August 10, 2010. On April 14, 2011, Johnson also released a poetry book with her I Do...I Did! co-writer, entitled Two Different Walks of Life. Her sophomore novel was Peaches & Cream, and her newest book of diary entries Stupid Guys Diary was released August 2014 . Writing has become Johnson's second career choice; she is also the Executive Director for Dimez magazine, and a contributing Writer for Temptation magazine and Glam Couture magazine, where she does a monthly article titled "Cherie Picking". In 2016, she accepted a position at Fever magazine and will be writing the "Pulse" article.