The company responsible for importing Costco's Kirkland Signature Irish Whiskey is MISA Imports, per the back label. However, this doesn't necessarily indicate who makes it.

In 2022, MISA was working with Terra Spirits & Liqueurs, which produced the Mr. Whiskey Irish whiskey. This was likely the liqueur found in the Kirkland brand at the time.

As of December 2023, MISA Imports was still listed, but the company is no longer partners with Terra. They now partner with 3 Counties Spirit Company and Ballykeefe Distillery.

Both companies are likely candidates as the original distiller, each one creating whiskies with descriptions that are consistent with the generic description on Kirkland's Irish.

All in all, while these are both good guesses, it's difficult to pin down who exactly makes the sweet-smelling liquor inside the Kirkland Irish whiskey bottles.