Lupus Can't Stop Toni Braxton!

Toni Braxton won't let lupus derail her from tour ... she performed over the weekend with a heart monitor strapped to her chest.

Toni's "The Hits Tour" hit Savannah, Georgia Saturday night where she busted into song with with the monitor in plain view.

We're told doctors urged her to wear it 24/7 to detect chest pain, as well as oncoming heart attacks or strokes.

Toni was hospitalized twice this month ... the result of complications from the autoimmune disease.

She still sounds amazing.

BTW ... Birdman was front and center at Saturday night's concert.