The short answer is yes, and there are two layers of protection worth knowing about.
First, MasterCard's zero-liability policy means you won't be held responsible for unauthorised purchases. If someone uses your card without permission, that's MasterCard's problem to sort out, not yours.
Second, most Irish MasterCard casino online sites use 3D Secure authentication, the prompt your bank sends you to confirm a deposit is genuine. It adds about 10 seconds to a transaction and occasionally catches people off guard the first time, but it's genuinely useful protection.
Ireland is also in the middle of a significant regulatory shift. The Gambling Regulation Act 2024 established GRAI, Ireland's first dedicated gambling regulator, though its licensing regime is still being phased in. For now, every casino I recommend holds an MGA or equivalent licence. If a site can't tell you where it's regulated, walk away.