Amell -- who plays the show's star, Oliver Queen -- tweeted the news on Monday.
"Arrow," based on the comic book "Green Arrow," centers on billionaire playboy Oliver who comes home to fight crime after being stranded on a desert island for five years. The show also stars Katie Cassidy, Colin Donnell and more.
The series pickup doesn't come as much of a surprise. The October 10 premiere of "Arrow" brought the best ratings The CW had seen in three years, with 4 million viewers and a 1.3 rating in the key 18-49 demographic.
The CW has also ordered additional scripts for freshman dramas "Beauty And The Beast" and "Emily Owens, M.D.," which have both seen solid ratings.