Nilsen began a YouTube channel with the name Missglamorazzi on October 23, 2009, because she wanted to share her feeling of confidence with other people and push herself to overcome her fear of public speaking. She told herself to do something that scared her, and creating a YouTube channel fell under that category for her. In her videos she covers topics such as fashion, lifestyle and make-up. Nilsen currently has over 4 million subscribers.

In late 2014, Nilsen became a judge on the reality television show Project Runway: Threads. At the 2014 Teen Choice Awards and 2015 Teen Choice Awards, Nilsen was nominated for Choice Web Star: Fashion/Beauty.

From September 2015 to March 2016, Nilsen dated fellow YouTuber Hannah Hart.

On December 4, 2016, The Trevor Project awarded Nilsen the Trevor Digital Innovator Award. “With a powerful social presence, Ingrid has used Technology for the better and built a platform and voice to advocate for equality,” said Abbe Land, Executive Director and CEO of The Trevor Project. “She is a role model of her generation and truly is a beacon of hope. She continues to push boundaries and believes in the mission of The Trevor Project, making her the perfect fit for the award."

In February 2017, Nilsen and Shiseido-owned bareMinerals announced a partnership, and Nilsen became the face of the brand's two best-selling foundations. The partnership was one of the biggest deals between beauty brand and influencer to date.