In May 2010, a friend of St. James, who is a Director of photography, sent her a clip of The Wedding Day from the New Sensations Romance Series because he was impressed by the quality of the film. After researching The Romance Series, she discovered that New Sensations was doing a writing contest for the series. Adult film Director Eddie Powell gave her advice on how to write a porn script after she contacted him on Twitter. She entered the contest in 2011 and her script, Dear Abby, won. Powell directed the film and New Sensations released it in June 2011. St. James also won Best Screenplay for the film at the 2012 AVN Awards.

Some of St. James's most notable works are Torn, The Temptation of Eve, and The Submission of Emma Marx. She co-directed Torn with Eddie Powell and it won the AVN Award for Best Romance Release in 2013, the year in which the category was first created. In 2014, The Temptation of Eve and The Submission of Emma Marx won AVN Awards for Best Romance Movie and Best BDSM Movie, respectively. That same year, St. James began to direct mostly for Digital Sin's Tabu Tales, a line with plots featuring sex between stepfamily members. In 2014, she became only the second woman after Stormy Daniels to win an XRCO Award as Best Director (Feature), an honour she could retain in the following two years. In 2015 and 2016, she also received the XBIZ Award for Director of the Year – Body of Work. In 2016, she co-created a Showtime erotic series, Submission with Paul Fishbein.