London-born Powley began acting as a teenager, starting out in the CBBC series "M.I. High". She became known to wider audiences for her portrayal of Princess Margaret in "A Royal Night Out" and as Minnie in "The Diary of a Teenage Girl", with both roles receiving much critical acclaim. Recently, she starred alongside Pete Davidson as his love interest, Kelsey, in "The King of Staten Island". No stranger to theatre, Powley has appeared in the West End and notably as Thomasina in the 2011 revival of "Arcadia" on Broadway.
Playing the part of Birdy, Powley was a fan before being cast in the role. "I was a huge, huge fan of this book when it came out and I think a lot of millennial women were. It feels really special. Everything in this show is completely relatable to me," she told the BBC.