Gatlin, starting in lane number four, held his form and powered through the second part of the Diamond League race at the Stade de la Pontaise with his traditional late drive, clocking 9.75 seconds.
Jamaican Asafa Powell finished second in 9.92 seconds, with American Tyson Gay in third on the same time.
At the age of 33, there is no doubt Gatlin is currently the sprinter to beat.
The 2004 Olympic 100-metre gold medallist and 2005 double world sprint champion who subsequently served two doping bans before nailing the 2012 world 60-metre indoor title, Olympic bronze at the London Games and a world silver in Moscow a year later, is peaking perfectly for next month's world champs in Beijing.
"I used this as a semifinals and Monaco (next week) will be a final, then I'll go home and get ready for the world championships," he said.
"No disrespect, I went into the race not thinking about my opponents, I just wanted to execute my phases," Gatlin said.
"I had a traditional fast start, tried to dominate through the middle and carried on through to the finish line and that's what I did.
"There's no message to Usain (Bolt), I just go out there and try and dominate."
The UK's Mo Farah marked a dramatic season debut in the men's 5,000-metre race, the first outing for the Olympic and double world champion since doping allegations against his coach Alberto Salazar.
Farah held his nerve to kick back in a supreme show on the final lap from 80 metres out to beat Ethiopian Yomif Kejelcha.
"This victory is also a way to answer some of the critics regarding my coach that came out lately," said an emotionally-charged Farah.
Claims made by BBC Panorama and US investigative website ProPublica alleged that Salazar broke doping rules by administering testosterone to American distance runner Galen Rupp in 2002 when Rupp — a training partner of Farah — was only 16, and encouraging misuse of prescription drugs.
Salazar has refuted the claims, and Farah was not implicated for any wrongdoing, insists he is "100 percent clean" and has welcomed subsequent probes by both the British and US anti-doping agencies to help clear his name.
"The last couple of weeks have been hard for my family and everyone else," Farah said.
"But what can you do? You just want to run and that's what I did and I enjoyed it."
One of the stand-out events at the August 22nd-30th Beijing worlds will surely be the men's triple jump, with world silver medallist Pedro Pablo Pichardo of Cuba and Olympic champion Christian Taylor pushing each other to their limits.
In another outstanding competition at Lausanne's Pontaise stadium, American Taylor sailed out to 18.06 metres, the Cuban content with second (17.99m) as both consistently nail jumps around the 18m mark in search of Jonathan Edwards' longstanding world record of 18.29m.
There was no joy for Kenya's David Rudisha in the 800 metres, the Olympic champion and world record holder edged into second by Botswana's Nijel Amos, who clocked a season's best of 1:43.27.
A strong US track presence was boosted by victory for Allyson Felix in her preferred 200 metres, having already garnered 2012 Olympic gold, two Olympic silver medals, and three world championship golds.
"It's the 200 metres and I love this race, it's always my favourite," said the 29-year-old after her 22.09-second win, with Dutchwoman Dafne Schippers in second (22.29).
Dawn Harper-Nelson earlier led an American cleansweep of the women's 100-metre hurdles, her 12.55 second finish seeing off teammates Jasmin Stowers, Queen Harrison and Sharika Nelvis.
But Shaunae Miller of the Bahamas, in 49.92 seconds dominated the women's 400-metre race, denying further American joy with Olympic champion Sanya Richards-Ross in second (51.12).
Germany's reigning two-time world shot put champion David Storl recorded a personal best and meet record of 22.20 metres to
beat American duo Joe Kovacs (21.71) and Reese Hoffa (21.30).