Pennsylvania becomes the second state in which FanDuel operates its online and mobile platform, following New Jersey.
FanDuel initiated a multi-channel marketing campaign to promote the launch, including TV, digital and radio ads.
The app is available on iOS and Android platforms with in-play betting and what it describes as fast payout options.
FanDuel said it will pull on its experience from New Jersey and focus on customer experience in this new market.
FanDuel launched its first retail sportsbook in New York at Tioga Downs Casino Resort in Nichols last week.
The other operators currently operating sportsbook apps in Pennsylvania are SugarHouse, Parx and BetRivers.
DraftKings, FanDuel's main competitor in New Jersey, is yet to launch a sportsbook app in Pennsylvania, but a future launch is expected.
