Videos of the incident at the Wicked: For Good movie premiere have been circulating widely on social media.
Wen is seen jumping over a barricade at Universal Studios Singapore before running towards Grande.
He then puts his arm around her, jumping up and down, with co-star Cynthia Erivo rushing in to break his hold.
Security officers tackled and removed the man, escorting him out of the venue.
Wen, a content creator who goes by the online moniker Pyjama Man, has posted several videos on his social media accounts showing him rushing towards other artistes, such as Katy Perry and The Weeknd.