"Just felt like we needed somewhat of a spark,'' coach Matt Rhule said of the quarterback change. "Sam will be our quarterback next week. He will be our quarterback moving forward.''
The decision came four days after Rhule said he had "bought in'' on Darnold as his quarterback when asked about the possibilities of Carolina pursuing a trade for Houston's Deshaun Watson.
"I believe Sam is going to be a great quarterback for the Carolina Panthers, and I haven't done any work on anyone else,'' Rhule said Thursday on a conference call with Giants beat writers. "He's my focus, and I expect him to play his best football moving forward.
"I'm not looking anywhere else.''
Rhule turned to backup P.J. Walker with 12:41 remaining Sunday and Carolina trailing 15-3. Darnold had an intentional grounding penalty from the end zone in the first half that resulted in a safety. He also had an interception near the New York goal line on a poorly thrown ball.
It was his seventh interception in the past four games after throwing only three in Carolina's 3-0 start. Sunday's loss dropped the Panthers to 3-4.
"Throwing on time, taking the open receiver, being patient, protecting the football, not throwing off his back foot,'' Rhule said of what has been different about Darnold the past four games. "He had some times on third down where guys were open. We're predetermining the thinking. Again, I can understand young quarterbacks go through that. We're obviously not coaching Sam well enough.
"This isn't about Sam. We needed more from the run game. We needed some explosive plays. We needed some big catches.''
Darnold was 9-of-18 for 52 yards and the interception against standard pressure, according to ESPN Stats & Information research. He entered the game with a 61% completion percentage on those plays, second worst among qualifying quarterbacks.
"I've been on record,'' Rhule said. "Quarterbacks go through ups and downs. Sam's got to take care of the football. Sam's got to throw on time. If it's not there, he's got to find a checkdown. We can't be driving with a chance to take the lead and throw an interception.
"His sense of urgency this week, I expect to be heightened.''
Sunday's game was Darnold's first game at MetLife Stadium after he spent the first three seasons of his NFL career with the New York Jets, who traded him to the Panthers this offseason. He was 8-11 at MetLife with the Jets.
Rhule said he never wants to embarrass any player, but just felt Darnold had reached the "tipping'' point where a change needed to happen.
Asked if he was embarrassed, Darnold said: "When you get to that point, getting pulled, I just internalize it. Honestly, it's more of those situations where it is what it is. He thought at the time that would provide a spark putting P.J. in there.''
Walker finished 3-of-14 for 33 yards and also had one run for 13 yards during his time in the game.
Rhule doesn't expect Sunday's decision on Darnold to change how the Panthers approach the trade deadline on Nov. 2 in terms of looking for another quarterback.
"I can't look to the future, but I don't believe it will,'' he said. "Everyone is disappointed now. There's emotions flying around. You saw the game. It wasn't good in many regards.''
Rhule reiterated his focus is on getting Darnold ready for Atlanta next week.
"We're not winning right now,'' he said. "It's going to take all of us. He just needs a lot of help from a lot of guys right now that he's not getting. I see the good moments, too. We're going to keep coaching him.''