"I wrote this song after my last 'Saturday Night Live' appearance," she said, introducing the mournful "Catch Me When I Fall."
She belted out the song with gusto, the only boost seeming to come with a brief echo effect on her vocal in the chorus. When she was done, Simpson smiled and hopped in relief.
It was nearly a year after Simpson's embarrassing appearance on the same stage, where her voice was heard singing the wrong song when she held her microphone at her waist. She danced an awkward jig and then walked off the stage.
The fakery made her a laughingstock and Simpson was booed lustily when she appeared at the Orange Bowl a few months later.
Leading up to this week's appearance, "Saturday Night Live" executive producer Lorne Michaels promised it would be her singing not some tapes, when she went on the air.
"Who will be the one to save me from myself?" the 21-year-old Simpson sang in the ballad. "Who's going to catch me when I fall?"
Later in the show she came back for a peppier number, "Boyfriend," where her vocal was augmented by a backup singer.
"Thank you so much!" she said at the end, blowing a kiss to the audience.
Even though lip-synching has been around for years, the incident resulted in Simpson being lampooned as an example of today's style-over-substance culture.
Simpson's manager-father, Joe Simpson, has said she used "extra help" because acid reflux disease had made her voice hoarse.