France lock Yoann Maestri and Tonga prop Alisona Taumalolo were shown a red card for fighting soon after the restart.
The hosts ran in four tries and Morgan Parra kicked 16 points to secure France only their second victory of the year. The French finished bottom of the Six Nations championship with just one success over Scotland and had lost their four encounters against world champions New Zealand since then.
Guitoune was quick to make an impact after flyhalf Remi Tales set him up on the right wing with a neat kicked pass.
"It's a beautiful night for me and for France. We needed that win because it had been a long time," Guitoune told broadcaster France 2.
Damien Chouly added a second try just before halftime, soon after Taniela Moa had been sin-binned, to extend the French lead to 21-6 at the break.
Maestri and Taumalolo were dismissed a minute into the second half, and it was France who re-organised faster with Brice Dulin touching down.
Fetu'umoana Vainikolo eventually scored a deserved try for Tonga, and then after France had reasserted with replacement Benjamin Kayser crossing, grabbed another consolation score just before the whistle.
