Allman managed a best of 69.50 metres, with China's Feng Bin claiming silver in 67.51m and Croatia's Sandra Elkasevic taking bronze (67.51).
After winning the Olympic title in Tokyo, Allman claimed two world medals – bronze at the 2022 championships in Oregon and silver at last year's event in Budapest.
But the American is unbeaten this year and carried her form through to the final in the French capital in some style.
France's veteran thrower Melina Robert-Michon, in a record-equalling seventh Olympic Games for a track and field athlete, finished 12th and last with a best effort of 57.03m.
The 45-year-old was a flag bearer for the host nation at the opening ceremony and hopes to continue to next year's world championships in Tokyo.
