Under the watch of her LA Boxing trainer Sean McCully, Toughill debuted in mixed martial arts on September 27, 1999, and fought to a draw with Irma Verhoeff at World Vale Tudo Championship 9 in Aruba.
She counts IBF Super Middleweight contender Librado Andrade, a long-time sparring partner, among her close friends.
After going 1–1–1 in her first three bouts, Toughill won five straight fights before losing due to illegal hits to the spine [1][2] in the finals of the 2004 Smackgirl World ReMix Tournament to Megumi Yabushita.
Despite cutting over 20 pounds (9.1 kg) to make the contracted weight limit, Toughill was victorious and later went on to defeat Karen Williams and Emily Thompson in subsequent events for PFC after a fight with Adrienna Jenkins was cancelled due to injury.
[13] Toughill was scheduled to compete outside of Strikeforce against China's Bao Yu Dan at Martial Combat 9 on September 15, 2010, in Singapore.
[16] Toughill agreed to face Anna Barone at BlackEye Promotions 5 on October 1, 2011, in Fletcher, North Carolina,[17] but withdrew from the fight after suffering a rib injury in training.
[20] Erin married Neil Melanson, a grappling coach and lead Jiu-Jitsu instructor at Xtreme Couture, in a private ceremony on November 20, 2009.
[23] Toughill's younger sister, Megan, was killed in a car accident on September 19, 2004, which was about three weeks before her title fight with Yvonne Reis.