Smolders stormed to victory in the LGCT to retain his lead at the top of the overall standings, then guided his team the Hamburg Diamonds to the top of the leaderboard.
"I am very happy," Smolders told Global Champions Tour TV. "To win the team competition and the Grand Prix on the same day with the same horse is very special. It was a fantastic weekend."
Riding Emerald N.O.P., the 37-year-old left all rivals trailing in his wake to finish 1.19 seconds ahead of Briton Scott Brash and scoop the €99,000 ($113,500) first place prize.
The tough course -- which sat in the foreground of the Château de Chantilly -- claimed many victims during the afternoon, most notably Smolders' nearest challenger Alberto Zorzi who now has a daunting 57-point gap to bridge.
Home favorite Philippe Rozier completed the podium in Chantilly, while Smolders' compatriot Maikel van der Vleuten makes up the top three in the overall standings.
Diamonds shine bright
Meanwhile, in the Global Champions League, Smolders and teammate John Whitaker showcased nerves of steel in their final runs to send the Hamburg Diamonds top of the overall rankings.
Dutchman Smolders delivered a faultless round earlier in the day but nearest rivals Miami Glory remained hot on the Diamonds' heels to put the pressure on Whitaker.
The Brit knew only a perfect round -- or one fence fault but with a faster time than the Glory -- would do to maintain their narrow lead.
Whitaker, riding Cassinis Chaplin, elegantly strode around the course, finishing with just one fault to wrap up victory for the Hamburg Diamonds.
The win sees the team overtake Valkenswaard United, who stuttered after Italian rider Alberto Zorzi's four-fault run on Friday, to lead the overall standings.
Sitting on 196 points, the Diamonds are 13 points ahead of Valkenswaard United and 24 ahead of the Mexico Amigos who rise to third place.