In addition to receiving a free Crunchy Taco Supreme, the first 20 taco-lovers through the door at each restaurant will also receive a limited-edition Taco Moon Party kit.
The kit includes intergalactic-level cool Taco Bell merchandise so fans can celebrate the Taco Moon with friends and family in style.
The offer is a part of Taco Bell's first-ever global campaign, when the saga of lunar phases ultimately displays its perfect half-moon shape.
“We’re so excited to invite Aussies to try our iconic Crunchy Taco Supreme for free on May 4th,” said Tamika Nelsen, Taco Bell's Marketing Manager.
“We hope that experiencing the Crunchy Taco Supreme ignites a love for our tacos in Australians like never before," Tamika said.
The promotion is limited to one Crunchy Taco Supreme per customer, and Taco Moon Party Kits are available for a limited time only, one kit per customer, while stock lasts.
The news comes after Taco Bell announced the opening of its new Sydney store, which will mark the brand's first-ever centrally located diner.
Located in Green Square, the new restaurant will open on May 4 - the same day as 'Taco Moon' day.
The opening day will feature giveaways of much-loved merchandise, including Taco Bell's signature oversized taco hats and fire sauce socks.