Megan Rapinoe opened the scoring for the reigning champions with a fine dipping shot from outside the area after 32 minutes, but they had to wait until 17 minutes from time to double their advantage through Abby Wambach.
Carli Lloyd rounded off an excellent team move for the third three minutes later.
Bruno Bini's side, who lost 4-2 to USA on Wednesday, went ahead a minute before the break as Laura Georges rose unmarked to head home Sandrine Soubeyrand's corner.
Elodie Thomis, Marie-Laure Delie, Wendie Renard and Camille Catala were also on target for the French.
Captain Casey Stoney set them on their way with a close-range finish in the 18th minute, with Jill Scott adding the second five minutes later.
Steph Houghton, the heroine of the opening win over New Zealand, sealed the win with her fierce strike eight minutes from time.
Brazil striker Cristiane grabbed a late winner to break New Zealand hearts at the Millennium Stadium.
The Football Ferns had frustrated Brazil thanks to a disciplined defensive display in this Group E encounter and looked set to boost Great Britain's hopes of topping the section by holding the Samba Queens to a goalless draw.
But Cristiane calmly lobbed Jenny Bindon five minutes from time after the New Zealand keeper's punch had gone straight to her.