The sighting nearly confirms that the Maroon 5 star, 34, and Sports Illustrated swimsuit model, 21, are an item.
Levine hinted at the Mexico trip on "The Voice" in its season four finale last week.
"I'm going to an undisclosed location where there will be tequila and sunshine," Levine said. He did not mention a lady would be joining him.
But Levine is no stranger to dating supermodels, having dated Victoria's Secret models Behati Prinsloo and Anne Vyalitsyna before Agdal.
Mexico photos of Levine and Agdal knocking around a volleyball are the first glimpse of the two together. Agdal was spotted on set for "The Voice" on May 23, followed by her sitting in the audience five days later.
Agdal's fame as a model is recent, but she made news earlier this year when she went with high-schooler Jake Davidson to prom after the teen got turned down by Kate Upton.