South Africa, who won 3-0 after leading 2-0 at half-time, reached the final with their victory, with a game to spare.
They face hosts Zimbabwe in their last round-robin match on Thursday.
Shelley Russell from Western Province scored twice and Marsha Marescia, who earned her record 251st Test cap, netted the third.
The South Africans put Ghana under immediate pressure at the start of the game, and Russell won the first penalty corner.
Cindy Botha injected the corner and Jade Mayne trapped the ball, with Tarryn Bright making a disguised pass for Russell, running in from the right, to score with a neat deflection.
Trailing 1-0 after six minutes, Ghana faced a mountain to climb as their opponents moved the ball with assurance, stretching the underdogs' defensive screen and making incisive breaks into the scoring zone.
Ghanaian goalkeeper Grace Mensah was on top of her game, however, and she made half-a-dozen early saves using various parts of her body and protective gear to keep the score respectable.
But there was no way out when SA cut through on the right, with neat interplay leading to Russell's second goal.
Ghana employed some heavy tackles as the match threatened to run away from them.
At the stroke of half-time, Kim Hubach's slap shot from SA's seventh penalty corner cannoned into the post.
Two minutes after the break, pacy Rachael Bamfo created excitement in the Ghana camp but her shot from inside the six-yard box was well saved by alert keeper Sanani Mangisa.
At the other end, SA made it 3-0 from their eighth penatly corner, an inch-perfect deflection goal by Marescia that sailed high into the net.
The rampant SA men, following an 18-0 thumping of Morocco and a 10-0 defeat of Zimbabwe, were set to tackle Ghana later on Monday.