In her youth, Macfarlane played basketball, but her aspirations in the sport came to a stop due to series of knee injuries. Macfarlane graduated Punahou School in 2009 in Honolulu, Hawaii. Although she got a scholarship for wrestling to Menlo College, she decided to study Anthropology at San Diego State University from where she earned Bachelor Degree in 2013. After earning her Bachelor Degree in 2013, she continued her education at SDSU to study Master of Arts in Liberal Studies.

Macfarlane began her amateur MMA career in 2014. She fought five times during that year, mainly with Xplode Fight Series, and went undefeated as an amateur.

Macfarlane’s first professional fight was an unsanctioned match against Katie Castro for Xplode Fight Series in 2015. Macfarlane won via technical knockout ten seconds into the bout. In the aftermath of the lopsided affair, the California State Athletic Commission (CSAC) launched an investigation into the organization’s unsanctioned MMA events. Castro had a 0-2 record before fighting Macfarlane and footage of the match was posted on the internet and labeled “Soccer mom loses to MMA fighter”. The video went viral, garnering over a million views on YouTube and was discussed on a few television news networks.

Following the bout with Castro, Macfarlane signed a three-fight contract with Bellator MMA. She made her debut in August 2015 at Bellator 141 where she defeated Maria Rios by split decision.

In her third title defense, Macfarlane faced Veta Arteaga at Bellator 220 on April 27, 2019. She won the fight via TKO due to a doctor’s stoppage in the third round.

Macfarlane made her fourth title defense against Kate Jackson at Bellator 236 on December 21, 2019. Macfarlane was victorious via unanimous decision.

In April 2020, Ilima-Lei, her sister Mahina, and one other female who chose to remain anonymous to the public filed a lawsuit against Punahou School for failing to take action over years of alleged sexual abuse from the school’s assistant basketball coach, Dwayne Yuen. In the lawsuit, all three allege Yuen of years of sexual abuse, harassment, lewd gestures, and showing young girls several pornographic photos.

On February 10, 2020, it was announced that Macfarlane had signed a ten-fight, five-year extension contract with Bellator.

Macfarlane is expected to make her next defense against undefeated challenger Juliana Velasquez on December 10, 2020 at Bellator 254.