A double from captain Mukarama Abdulai at Estadio Charrua steered the Black Maidens to a third straight win after 5-0 and 3-1 victories over the hosts and Finland respectively.
The West Africans topped Group A with nine points to set a quarter-final date with Mexico, who finished second in Group B on Sunday.
New Zealand, despite the defeat, join the Black Maidens into the last eight, having already booked their place before the final round of group games. The Young Football Ferns next play Japan.
After a barren first half, Ghana broke the deadlock of Tuesday's game in the 61st minute through Abdulai, who outrun Marisa Van Der Meer to latch onto Nina Norshie's lofted long ball to slot a shot beyond goalkeeper Anna Leat.
The Northern Ladies striker was not done just yet as she scored the second goal a minute to full-time. Having received a pass from Suzzy Teye, the 16-year-old once again beat Van Der Meer to create shooting space on her right before unleashing a shot into the net.
By Tuesday's double, Abdulai maintains her place as top scorer of the championship, but this time with six goals.
She will hope to continue her good form in Sunday's showdown against Mexico.