The actress recurred as the young, lesbian prostitute Betty Dimello, who helped Dr. Masters (Michael Sheen) in his research study of human sexuality in the first three episodes of the first season.
Her character was last seen in "Standard Deviation" leaving the hospital with her fiance (played by Greg Grunberg) after Masters' failed attempt to reverse her tubal ligation.
As a result of the promotion, Ashford will leave her Tony-nominated role in the Broadway musical "Kinky Boots," in which she plays factory worker Lauren. Her exit will occur sometime in March, while her co-star Stark Sands is also slated to depart the musical in early 2014.
Ashford's other Broadway credits include "Wicked," "Legally Blonde" and "Hair." She has also had small roles in the TV shows "Law & Order: SVU," "Smash," "Made in Jersey," "Nurse Jackie," "A Gifted Man" and "The Big C."
The first year drama, which co-stars Lizza Caplan as Virginia Johnson, was renewed for Season 2 in October along with "Homeland," which was picked up for a fourth season.
"Masters of Sex" continues Sunday nights at 10/9 p.m. CT on Showtime, with the season finale airing on Dec. 15.