Odoi-Atsem was in his 27th MLS appearance across four seasons, having missed most of 2018 and 2019 due to the effects of Hodgkin's Lymphoma. He has since recovered.
Donovan Pines added his second career goal -- and second in as many games -- as D.C. won during its third game under interim head coach Chad Ashton after the firing of long-time manager Ben Olsen.
Brandon Vazquez scored a second-half leveler for Cincy, which was looking for only its second back-to-back wins of the season. His goal was FCC's first from open play since he scored seven matches ago in a 1-0 win over the New York Red Bulls.
Both Cincinnati's Bobby Edwards and D.C.'s Chris Seitz made goalkeeping errors contributing to each team's first goal while each side's regular starter sat out. Pzemyslaw Tyton was listed as not medically cleared for FCC, while Bill Hamid was out a second game due to illness.
But on the deciding sequence, Edwards made a good low save to deny Kevin Paredes after Cincy was turned over in its own end. Unfortunately for him, the rebound fell directly to Odoi-Atsem on the right side of the penalty area, and he coolly slid the ball across the line from close range.
Pines put D.C. in front in the 36th minute. Yamil Asad drove a long free kick that was heading wide of the back post and out of play, but Edwards appeared to lose track of his location and attempted to catch it before going out of bounds. Instead, he spilled it directly in front of Pines, who took a couple quick touches and then finished into an open goal.
Cincinnati leveled exactly a half-hour later. Siem De Jong unleashed a dipping shot from just beyond the 18-yard shot that skipped awkwardly off the artificial turf. Seitz failed to hold it, and Vazquez was first to the rebound to direct it across the line.