The pop star had just finished playing at the venue on 22 May, 2017, when a terrorist detonated a homemade explosive device, killing 22 people.
Writing on Instagram, Grande shared a message of solidarity with the victims.
"Not a day goes by that this doesn't affect you and all of us still," the 26-year-old wrote.
"I will be thinking of you all week and weekend."
Acknowledging "the sadness and tremendous heaviness of the anniversary", she added: "My heart, thoughts, prayers are with you always."