Three weeks after going into cardiac arrest during a prime-time N.F.L. game, Buffalo Bills safety Damar Hamlin made his first public appearance Sunday at his team’s divisional round playoff game against the Cincinnati Bengals.

The CBS broadcast showed Hamlin riding into the stadium in a security vehicle and walking into the team’s locker room less than an hour before kickoff.

The last time the two teams were on the field together, on Jan. 2, Hamlin collapsed after making what appeared to be a routine tackle of receiver Tee Higgins. Hamlin stood up after the play but then fell to the turf. Medical personnel administered CPR and restarted Hamlin’s heart before taking him off the field in an ambulance, as players and coaches looked on in anguish.

Since then, Hamlin, 24, has made steady progress. He was released from a hospital in Buffalo on Jan. 11 and visited the Bills for the first time last weekend in advance of their 34-31 wild-card playoff win against the Miami Dolphins.Hamlin watched that game at home with his parents, Nina and Mario, and his younger brother, Damir.

Bills players said being around Hamlin and seeing his progress has buoyed them, helping them push forward during what they hope is a long postseason run. On the line on Sunday is a trip to the A.F.C. championship game, a potential rematch of the 2021 matchup with Kansas City. If the Bills advance, that game would be held in Atlanta, the neutral site the N.F.L. selected because the cancellation of the Bills-Bengals game meant that Buffalo played one fewer regular season game than Kansas City.

Coach Sean McDermott said last week that Hamlin had been at the team facility “almost daily,” though his activities have still been limited. McDermott said on Wednesday that Hamlin was not yet taking part in team meetings and was taking it “one baby step at a time” as he tried to return to daily life after his medical emergency.

The regular-season game between the Bills and Bengals was suspended after Hamlin’s collapse, which occurred at the 5:58 mark of the first quarter. The N.F.L. canceled the game three days later.

“That experience, we’ll carry that with us,” McDermott said at a news conference. “There’s a challenge to that, but there’s also a lot of good that came from that. And I think right now we need to focus on the positive, and the positives that came out of that, as opposed to the other piece of it.”

Hamlin’s marketing representative, Jordon Rooney, told The Associated Press on Thursday night that Hamlin still faces a lengthy rehabilitation. After his collapse, Hamlin spent nearly a week in the intensive care unit at a Cincinnati hospital, where he was intubated for about three days. Hamlin’s neurological function is intact and he is able to walk and talk, but the doctors who cared for him in Cincinnati said recovery from a life-threatening event like the one Hamlin endured can take weeks or months.

“Damar still requires oxygen and is having his heart monitored regularly to ensure there are no setbacks or after effects,” Rooney said in a statement. “Though he is able to visit the team’s facility, Damar is not in position to travel often, and requires additional rest to help his body heal.”

Bills safety Jordan Poyer said in a news conference last week that the biggest emotional hurdle for Hamlin’s teammates to clear was playing the New England Patriots six days after Hamlin’s collapse, in their final game of the regular season. He said Hamlin’s presence around the team since then “brings everybody’s spirits up.”

As the Bills face the team against whom the near tragedy happened, Hamlin will be in the building to provide that boost for what is his team’s biggest game of the season yet.