Riding Chaman, the 49-year-old made his experience count in the jump-off, edging out young American rider Reed Kessler on Cylana by two tenths of a second.
Sweden’s Rolf-Göran Bengtsson took third on Quintero La Silla.
Beerbaum collected 200,000€ for his efforts in the sunshine under the glass roof of the famous exhibition hall in the French capital.
Of the 38 pairs on the starting list, just 14 qualified for the jump-off after clear rounds.
In the finale, four managed to complete the course without incurring penalties: Beerbaum, Meredith Michaels-Beerbaum, Kessler and Bengtsson.
Multi Olympic medallist Beerbaum, riding his faithful bay stallion, clocked a time of 38.33 seconds, which proved unbeatable.
Kessler, who only started competing in Grand Prix 5*events in 2012, claimed an honourable second with a time of 38.53 seconds.
European title holder and backbone of the Swedish team Bengtsson came in third in 39.26 seconds.
The American teenager and the Swede both took to Twitter after the Paris event to express their delight with their horses’ performances. Kessler described her mount as “amazing” while Bengtsson said Quintero La Silla “felt really great today”.
Germany's Michaels-Beerbaum, the only woman to have held the number one spot in the world rankings, completed the jump-off standings after a time of 40.95 seconds with Bella Donna.
In the Prix de la Ville de Paris, Katharina Offel took the honours riding Cathleen 28.
The Ukrainian beat American Kent Farrington on Blue Angel, with Ireland’s Denis Lynch third on Lantinus 3.
France’s Pénélope Leprevost, partnering Nice Stephanie, finished just out of the podium places in fourth.