The sprinter, whose gold at last year's Paris Olympics, was the first ever for her tiny Caribbean island homeland of Saint Lucia, clocked 10.76 seconds for the win at the Letzigrund Stadium.
Ivorian veteran Marie-Josee Ta Lou-Smith was initially disqualified for a false start.
A second set saw Alfred, in lane four, clean out of the blocks.
She kept the pressure on through to the line for a fine victory that was the perfect tonic before departing to the September 13th-21st world championships in Tokyo.
Jamaica's Tia Clayton finished second in 10.84sec, with Britain's Dina Asher-Smith rounding out the podium (10.94).