The 28-year-old actress was overjoyed after Christopher, who she first went public with in December 2012, popped the question on the top of the Empire State Building in New York, reported Us magazine.
"Best night of my life. We're on top of the world," Tisdale posted on Twitter.
While friends say Tisdale wasn't surprised by the proposal, she was thrilled by Christopher's choice of location.
"He had been planing on it for awhile. I think she knew it was coming but she is so happy," a source said.