"Got the great news tonight that #GirlMeetsWorld was picked up for 8 more episodes - a total of 21! Can't wait for everyone to see them all," Fishel tweeted Thursday.
The "Boy Meets World" spinoff is expected to premiere later this year, EW.com reported.
Former "Boy Meets World" child stars Fishel and Ben Savage will reprise their roles of Topanga and Cory, who are now the parents of a 12-year-old daughter, played by Rowan Blanchard.
"'Girl Meets World' is a new show for a new generation that will be rooted in the same kind of honest, comedic storytelling about coming of age and the importance of family and friendship that made 'Boy Meets World' so popular," Michael Jacobs, a producer on both "World" sitcoms, said in a statement last year when the spinoff was announced.
"Boy Meets World" ran for seven seasons on ABC, wrapping up in 2000.