Can British-Irish dual nationals use an Irish passport to visit Gibraltar?

Short answer

Yes. A British-Irish dual national travelling on an Irish passport is treated as an EU citizen on entry to Gibraltar and the Schengen area, and is not subject to the Schengen 90-day limit, EES or ETIAS. Travelling on the British passport means the rules for UK citizens apply.

Detailed answer

The Government of Gibraltar does not advise on which passport to use and recommends taking independent advice. Whichever passport you choose, use the same one throughout the trip so that entry and exit records match.

Staying in Gibraltar itself for longer than 90 days requires taking up residence through the Department of Immigration and Home Affairs, whichever passport you hold.