The 46-year-old singer last debuted new music on her album Laws of Illusion in 2010.
"Everyone kept saying, 'Where's your album?!'" McLachlan tells E! News. "Pressure!"
"It isn't about just one thing," the singer says of the new single. "It started out as a song about bullying, and then Malala [Yousafzai] was shot by the Taliban and that story became big news. She sort of became an inspiration for finishing the song."
"It is very much a female empowerment song," McLachlan concludes. The songstress has two daughters and says, "I'm very pleased when I can talk about somebody in the world who is doing something really important and helpful and quite selfless."
McLachlan plans to go on tour to promote the new album, but hasn't quite decided what she wants her return to be like.
"I am a musician first and foremost...and I think the songs are strong enough that I don't want to put on a spectacle," the singer says. "I just want to take people on a journey and music is the first and foremost important thing in that."
Shine On will debut on May 6, and McLachlan begins her new tour on June 20 in Seattle. Listen to "In Your Shoes" here.