Yes. Banks have security systems in place that ensure fraudsters can't hack into your account, whether you're logged in online or on your phone. But you still need to be careful – never ever send your online/mobile banking information to anyone.
If you're using a mobile app, make sure you download your bank's official mobile app from your app store and make sure you update the app regularly with any new security features.
It's also worth keeping your computer up to date with Free Antivirus Software, so you're protected from viruses and spyware.