The pair began dating shortly after Ariana broke up with rapper boyfriend Mac Miller, and have been affectionately flaunting their love on social media.
Davidson also confirmed that he had split from his longtime girlfriend Cazzie David in mid-May, around the same time he wrapped his fourth season performing on Saturday Night Live.
Davidson also debuted two new tattoos this week - both inspired by his new girlfriend.
Both Grande, 24, and Davidson, 24, are yet to confirm their engagement.