Overall, yes. In the past, mobile banking was less secure. But these days, leading banks are prioritizing cybersecurity. As such, you can expect to see a variety of security measures in place, with features like two-factor or multifactor authentication, full encryption, and round the clock fraud monitoring.
That said, never assume that your bank is 100% secure because no bank is. Take steps to protect your password, and add a passcode on your mobile so that no one can access your bank account if you lose it.
Finally, when vetting mobile bank apps, look for red flags that might indicate a company is not serious about security. Generally speaking, this is going to be reflected in the apps' reviews.