Azurá Stevens added 18 points, Jordin Canada 15 with nine assists and six steals and Layshia Clarendon 14, including the clinching free throws with 11.2 seconds left for the Sparks.
The Sparks (15-18), who have battled injuries all year but started the same lineup for the seventh straight game, pulled into a tie with Washington for the seventh playoff spot 2½ games ahead of Chicago.
Cheyenne Parker led the Dream (16-18) with 22 points. Rhyne Howard had 15 points, Danielle Robinson 12 and Monique Billings had 10 with 10 rebounds.
Dearica Hamby’s three-pointer with 6:32 to play put the Sparks up for good at 71-68. Ogwumike had six straight points down the stretch to hold off Atlanta, which has lost five of six.
The Dream made all five of their three-pointers and shot 64% in the first half to open a 52-39 lead at the break. Atlanta turned a two-point lead near the middle of the second quarter into an 16-point lead when Howard drilled a three 14 seconds before halftime.
The Dream took 64-62 lead into the fourth quarter.
The Dream missed all five threes after the break and finished with 48% shooting.
The Dream were without All-Star guard Allisha Gray for a second-straight game with an ankle injury. The team announced Thursday Nia Coffey would miss the remainder of the season with a hand injury.