And what a dramatic win it was for the Frenchwoman.
The 26-year-old managed to pull off a winning move after seven minutes in golden score time to defeat home favourite and world number three Miku Tashiro in a repeat of last year's final.
Both finalists ended up in tears and shared a warm embrace.
With four gold medals (three consecutive) at the World Championships, Agbegnenou overtakes Gevrise Emane as France's most successful female athlete in the competition.
An exhausted Agnegnenou said afterwards, "I feel very honoured. I hope this win can inspire my teammates to win other medals.
"When I started judo I would have never imagined I could become world champion even once." - Clarisse Agbegnenou on winning a fourth world title
The Rio 2016 silver medallist demonstrated once again that she's a born fighter!
'The hardest final'
For both judoka, the final was their fifth bout of the day and by far the longest.
After four minutes of regulation time and seven minutes of golden score, there was still no score in a gruelling and nailbiting contest.
Tashiro had looked the more likely to win but after she just failed with an ouchi gari leg sweep, she hesitated and Agbegnenou countered with a maki komi throw for a waza-ari score and victory.
"This final was crazy, really crazy. I’m happy to have fought Miku Tashiro because this woman is - I will say it - best also", world champion Agbegnenou told reporters after the win.
"I like this girl because she’s respectful, she’s a big fighter, and we can always learn from each other.
"The final was the hardest in a really, really long time and now I can say that I went with my mind, my head because my body didn’t want to go. I could not find any technique to throw her, it was really hard.
"I said, 'No, no she can’t take me, I want this medal again!'" - Clarisse Agbegnenou after winning fourth world title.
"When I heard the crowd, it was like half Tashiro, half me, and I felt like I had to do it. In my head I could not give up. I didn’t know if I threw her or what. I just looked at the referee and I saw that he did waza-ari and it was like, it’s over!
"I think I threw her with the same technique last year and I guess it worked again. But I think I need to work on another technique because it probably won’t work anymore."
Tashiro has now lost eight of the nine head-to-heads with Agbegnenou.
The only time she came out on top was in the final of the 2017 Masters in St. Petersburg.
"I lost again and I’m having a hard time accepting this result," the four-time judo world medallist told Japanese press.
"I felt good during the match and I thought I had her. But all it takes is one moment to decide a contest like this.
"Now it’s back to the drawing board for me in trying to win a gold next year."
"It comes down to heart. At the end of the day, whoever wants it more wins and today proved I don’t have enough desire." - Miku Tashiro
Germany’s Martina Trajdos won bronze by default as Slovenia's Olympic champion Tina Trstenjak was disqualified in the semi-final for trying a throw after an arm lock, an illegal move.
World number five Juul Fraanssen took her second career bronze against fellow Dutchwoman Sanne Vermeer.
Gold for Israel
In the men's -81kg final, Sagi Muki defeated Belgium's Matthias Casse to add a world title to his European Games and European Championship crowns.
It was the first gold for him and for a male Israeli judoka at this event.
The world number two stormed to the final and comfortably beat all his opponents, including Egypt's Mohamed Abdelaal, who was booed by the crowd after refusing to shake hands after the match.
"It’s a very special moment not only for me but for my country." - Sagi Muki
"It's a very special emotion for me. I am 27 and I finally did it!" Muki said during the post-match press conference.
"Judo is a leading sport in Israel. Any medal gives a lot of emotion to Israeli people. Many fans came from Israel to support me and this was a special occasion to connect us even more."
Before the final, the Israeli judoka received a call from his country's prime minister Benjamin Netanyahu, who later congratulated him on social media.
Earlier in the competition, reigning world champion and top seed Saeid Mollaei knocked out Rio 2016 gold medallist Khasan Khalmurzaev.
But then the Iranian, who turned up with his head heavily bandaged, lost the semi-final and the small final.
The bronze medals went to Canada's Antoine Valois-Fortier and Georgia's Luka Maisuradze.