She is known for her role as Riley Matthews on the Disney Channel series Girl Meets World that aired from 2014 until 2017. From 2017 until 2018, she made appearances on The Goldbergs as Jackie Geary.

Blanchard was born in Los Angeles, California, to Elizabeth and Mark Blanchard-Boulbol, who are yoga instructors. Her paternal grandfather was an immigrant from the Middle East, who had paternal Syrian ancestry and maternal Armenian ancestry,and her paternal grandmother's ancestors are from England, Denmark, and Sweden. Her paternal great grandparents had met in Aleppo, present-day Syria. She was named after a character in Anne Rice's The Witching Hour. Rowan has two younger siblings, Carmen and Shane.

Blanchard began acting at the age of five. In 2010, Rowan was cast as Mona's daughter in The Back-up Plan and was in the main cast of the Disney Junior Original Series Dance-A-Lot Robot as Caitlin. In 2011, she was cast as Rebecca Wilson in Spy Kids: All the Time in the World, and as Raquel Pacheco in Little in Common. In late January 2013, Blanchard was cast as Riley Matthews in the Disney Channel series Girl Meets World. She also sings the title song, along with co-star Sabrina Carpenter. The titular character is the daughter of Cory and Topanga from Boy Meets World. She is an active member of Disney Channel Circle of Stars. In early January 2015, Blanchard was cast as Cleo in the Disney Channel Original Movie Invisible Sister.

In September 2017, Blanchard announced that she would be releasing a book, titled Still Here, which was published in February 2018. Blanchard also co-starred in the feature film adaptation A Wrinkle in Time, which was released in March 2018