The two stars were spotted visiting Disneyland in Anaheim, Calif. on Monday.
Fans saw the couple board Space Mountain yesterday evening. As a video from Twitter user @reginaleigh95 shows, the singer wore Mickey Mouse ears for the magical occasion.
"Ariana and Pete were in the front row and he got out first and then turned to her and held out his hand to help her up," an eyewitness told E! News. "A few people yelled ‘Ariana' from the line and she turned and smiled at them and waved. She looked very happy. Then they all walked out and Ariana and Pete were holding hands."
When asked if she could spot Grande's engagement ring, @reginaleigh95 tweeted Grande's "sweater paws were covering [it]."