Mariana Cadena and Jessica Morales scored two goals each and Vivian Vega had another in the first half, capitalizing on several howling mistakes by Bahamian keeper Cori Strachan, to give Mexico six points and keep it just behind the United States in Group B on goal difference.
The result assured the Mexicans - as well as the United States - of a berth in the knockout round next Thursday. The Americans, who beat Trinidad & Tobago 5-0 earlier Saturday, will face Mexico on Monday for the group title and semifinal seeding.
The loss eliminated Bahamas, which is playing in the finals of a CONCACAF championship at any level and has been outscored 15-0 in its two matches so far. Trinidad also was eliminated from semifinal contention with the result.
After taking more than a half hour to break down Trinidad in their 2-0 win on Thursday, Mexico - which made nine lineup changes from its opening win -- needed only six minutes to go ahead of the Bahamas.
Cadena, who a minute earlier rounded Strachan only to touch the ball too far, ran onto a ball down the left side of the area and collided shoulders with Bahamanian defender Taj Dorsett. Dorsett fell, enabling Cadena to step back, recollect the ball and beat Strachan from 12 meters.
Morales doubled the lead two minutes later on the first of Strachan's gaffes.
Michelle Gonzalez settled a throw-in on the right and looped a cross into the goal box, where Strachan got her hands on but couldn't control. She let it drop in front of her where Morales had an easy touch for the goal.
Morales made it 3-0 when Strachan came out to try to intercept Natalie Rivas' low, rolling cross to edge of the six, but again failed to grab it. The ball deflected up off the face of Morales, who reacted quicker and pounced on the loose ball.
Strachan's most egregious error came in the 26th when Vega hit a seeming harmless shot from 25 meters, but the Bahamian keeper failed to get low and the ball slipped through her hands and between her legs.
Cadena scored her second in the 43rd when Strachan raced off her line to intercept a long ball to the edge of the penalty area. She failed to get the ball, enabling Cadena an easy finish into an open net.
Bahamas coach Daria Adderly replaced Strachan at the start of the second half with Sheryl Evans, who didn't play in any of the team's five Caribbean qualifiers.
She made several athletic saves to thwart Mexico, her most dramatic in the in the 74th, reaching back with an extended left arm to swat away Cynthia Pineda's header from off the line.
She couldn't completely subdue a relentless Mexican offense, allowing Pineda's left-footed drive from 25 meters skip past her inside the right post in the 79th.
The Bahamas nearly scored its first goal of the tournament early. Kennadi Green broke down the left side in the 18th minute to run onto a long ball, With Mexican keeper Adela Meza off her line to try to defuse the danger, Green's attempted cross with the outside of her right foot struck Mexican defender Jessica Valadez and bounded toward an open net, only for Greta Espinoza to clear a foot from the line.
The Bahamas will have a final attempt for its first win when it faces Trinidad on Monday. It lost 3-0 to the Soca Princesses in December in Caribbena qualifying.