Fans at Paul Brown Stadium roared between the first and second quarters as the Bengals honored Leah, who's battling Stage 4 pediatric cancer.
The Bengals announced a $1.3 million donation to Cincinnati's Children's Hospital and Medical Center in Leah's name, and the giant video screen played a montage of Leah and Devon set to the song "Brave" by Sara Bareilles.
The Browns won the game 24-3, and Devon had three total tackles.
"I would describe it as an emotional roller coaster," he said afterward. "Seeing my daughter in the pregame with all the excitement and then seeing her on the field receiving the check and just seeing the joy in her face, I was just so proud of the perseverance she showed to raise that money."
Leah's story has touched millions through social media. She wore a bedazzled Still jersey and a pink-flowered headband while flanked by family members in a suite pregame.
On a night filled with touching moments, Browns quarterback Brian Hoyer made a point to embrace Devon Still during the ceremony.
"Being a parent myself, I couldn't imagine what he's going through, especially how demanding this job is," Hoyer told NFL Network after the game when asked what he told Still. "That gives you goose bumps. I just went over and told him I respect him and I pray for his daughter and him and hope everything gets better."
After the ceremony, Leah's grandmother carried her off the field and through the tunnel, where she was emotional.
"Because everybody loves you," the grandmother was overheard saying to Leah, minutes after chants of "Leah, Leah" trumpeted through parts of the stadium.
"Seeing her picture on the scoreboard made me emotional, but somehow I was able to play the game," Devon Still said. "The most emotional I got was when I looked up and saw her and Lauren Hill and saw they got a chance to meet."
A member of the family said of Leah as the group was walking toward the elevators and back to the suite: "She's taking it all in. She's been really into it."
Fans, TV producers and even local police donned a No. 75 patch or jersey in honor of Still. Devon Still wrote "Leah Strong" on his eye black strips.
Leah took a selfie with the Bengals cheerleaders in pregame:
She watched her father play live for the first time since he debuted in the NFL in 2012 as a second-round pick of the Bengals.
Leah is battling neuroblastoma, a rare childhood cancer that typically has a 50-50 chance for survival. Surgery to remove a cancerous tumor from her abdomen was considered successful, but rounds of radiation, chemotherapy and stem-cell treatments await her before doctors can determine whether she's cancer-free.
ESPN.com Browns reporter Coley Harvey and The Associated Press contributed to this report.