Eriksen came on in the 52nd minute to rapturous applause. Earlier this month, he said he told paramedics to keep his boots, citing that he "wouldn't need them," when he suffered cardiac arrest while representing Denmark in their Euro 2020 opener in June.
However, the midfielder completed his remarkable return to football on Saturday, making his debut for Brentford after joining the Premier League side in January. His side lost 2-0 to Eddie Howe's Newcastle, who continued their push toward safety.
"If you take away the result, I'm one happy man," Eriksen said. "To go through what I've been through, being back is a wonderful feeling.
"[Brentford coach] Thomas [Frank] didn't say much [when I came on]. I've been speaking to him every day for the last few weeks. He just said good luck and enjoy the game.
"You can never predict the game. I don't think anyone predicted we'd be down to 10 men so early. The guys did what they could. It was a good fight in the end.
"It's been very special since day one. [Brentford] have taken good care of me. Everyone's been really happy about it and everyone's been really helpful. Everyone is here. My family, my parents, my kids, my mother-in-law and some doctors who have been helping me back and forth. What they've been through is even tougher than what I've been through."
"It was a wonderful moment. That's definitely the thing that'll keep me smiling at the end. It was good to see him out there and it was good to see him show glimpses of what he is capable of," Brentford manager Thomas Frank said.
Eriksen was released by previous club Inter Milan after being fitted with an implantable cardioverter defibrillator (ICD) device, which is not permitted among professional athletes in Italy.
"The key thing is that everything has been checked and there is zero chance that something should happen," Frank said. "He and his family are aligned that he should play football, so that's very important."
"Also for everyone ... after you have had a cardiac arrest, that if it is a way out of it, you could have a normal life after you have been checked."
Speaking at his presentation as a Brentford player, just eight months after the incident, Eriksen described his ICD as his "protection."
"My ICD is here for my protection," Eriksen said. "It is in because, if anything would happen to me, there is no need for a defibrillator because I will have my own. It is really just extra security. I am more protected here than you guys.
"And that is how I feel. I feel very protected with it. I feel normal. I don't feel it in any annoying way. Only going through the airport, I have to go around instead of going through a scanner."
Eriksen previously played in the Premier League with Tottenham Hotspur, with whom he had a crucial role in helping the club reach the 2019 Champions League final.
On his aim for the rest of the season, he added: "First of all to get the feeling and touch back, that football feeling, and to help Brentford stay in the Premier League."