The singer was forced to pull out of the Benicassim and Optimus Alive festivals earlier this month due to a vocal cord injury.
Florence + the Machine kicked off their North American tour in Vancouver last night (July 21).
Welch spoke very little at the start of the gig, while her voice was "slightly strained" during the track 'Only for a Night', reports Rolling Stone.
The US music magazine compared the frontwoman to "a freshly-injured Olympic athlete running at about 80% of their speed".
Welch told the crowd: "It's wonderful to be up here, because I lost my voice for a while, and it seems like it's back.
"This song seems quite fitting because, well, it seemed to suit last week a bit, when I lost my voice. Dark times... but it's all better now."
Florence + the Machine remained top of the UK singles chart in this week's update with the Calvin Harris-remixed 'Spectrum'.