The Liz & Dick actress, 26, attended Justin Bieber's show with opening acts The Wanted and Carly Rae Jepsen.
Lohan has praised Bieber in the past, even comparing their mothers. She tweeted on Sept. 28, writing: "I think @justinbieber's mom Pattie Mallette & my mom @dinalohan are so strong for speaking out about their stories. It's women like this... who make a difference in the world.. They encourage us to be strong. Thank you to @dinalohan & pattie mallette for being such strong women."