Beginning in 1987, Weston carved out a career as a film and television actor, working steadily throughout her twenties in a series of mostly small bit parts. Her credits included the sitcoms Growing Pains, Who's the Boss? and Third Rock From The Sun, and the film Sister Act 2: Back in the Habit. Through about 1996, she was credited in her appearances as "Kimberlee Kramer".

In May 1997, and by now using the name Riley Weston, she began claiming her date of birth as 1979 in order to be considered for further acting roles. The deception was assisted by her small size: her height is 4' 11" and weight is 93 pounds.

In 1998, she began drafting screenplays and marketing herself to television studios as a recent high school graduate. She was soon hired by the WB Network as a Writer for the show Felicity after they saw one of her scripts about teenage sisters. Hailed as a child Prodigy and "wunderkind" she was featured on Entertainment Weekly's October 1998 list of the "100 Most Creative People in Entertainment", which described her as an up-and-coming 19-year-old. Shortly thereafter, she was offered a half-million dollar screenwriting deal with Disney.

She continues to work as an Actress, singer, voiceover Artist, and author. Weston's first novel, Before I Go, was published in September 2006. The book earned Weston a 2007 Independent Publisher (IPPY) award for Storyteller of the Year. Her debut novel also received the 2007 New York Book Festival Grand Prize and was named Best Fiction. Before I Go also received a Book Sense Pick. Weston's debut single, "If I Said Howdy to You", was released in late 2009.