The appeal was heard Tuesday afternoon.
Smith-Schuster was suspended for Monday night's vicious fourth-quarter block on Cincinnati Bengals linebacker Vontaze Burfict, who was in a defenseless posture, according to the NFL's ruling. Smith-Schuster then stood over Burfict as he lay motionless.
Smith-Schuster will miss the Steelers' home game against the Baltimore Ravens on Sunday night.
Steelers quarterback Ben Roethlisberger said Wednesday that he didn't believe Smith-Schuster should have been suspended, comparing the hit to one that Rob Gronkowski made Sunday that also drew a one-game suspension for the New England Patriots tight end.
"I didn't think it was warranted. Thought maybe a fine, pretty steep fine," Roethlisberger said. "Thought what happened, play that happened, happened in the context of a football play. [It] wasn't away from the ball, hit on a defenseless player, much bigger football player. Obviously we don't like the taunting, standing over him.
"I don't like to compare players and suspensions, [but] look at what Gronk did and what JuJu did. They got the same suspension. I don't know if that is necessarily fair, but that is above our pay grades."
Bengals safety George Iloka also received a one-game suspension for a hit on Steelers star Antonio Brown in the end zone in the fourth quarter when Brown was deemed to be a defenseless receiver. Brown held on to the ball for what resulted in the tying score.
Iloka's appeal was heard Tuesday evening, but a decision isn't expected until Wednesday, a source told ESPN's Adam Schefter.
With 7:10 remaining in Pittsburgh's eventual 23-20 victory over the Bengals, Smith-Schuster leveled Burfict as the linebacker pursued Steelers running back Le'Veon Bell on a 12-yard gain.
"The contact you made with your opponent placed the opposing player at risk of serious injury and could have been avoided," NFL vice president of football operations Jon Runyan said in issuing the suspension. "Your conduct following the hit fell far below the high standards of sportsmanship expected of an NFL player."
Runyan shared similar sentiments in issuing Iloka's suspension.
"The Competition Committee has clearly expressed its goal of 'eliminating flagrant hits that have no place in our game' and has encouraged the League office to suspend offenders for egregious violations such as the one you committed last night," Runyan said in his ruling.
Neither player was ejected from the game.
Smith-Schuster's actions after the hit upset Pittsburgh coach Mike Tomlin.
"I'll stand by my statement last night that his actions after the hit are more disturbing than the actual hit," Tomlin said Tuesday. "Those hits are teachable moments. He's a better sportsman than he displayed after the block. He has to work hard so people understand the type of man he is."
Smith-Schuster told reporters he "messed up" with the taunting, because he cost his team 15 yards on the penalty.
"I was just playing to the whistle," Smith-Schuster said. "I didn't mean to stand over him. I was trying to get a big block for Le'Veon Bell for him to get upfield. The unsportsmanlike conduct is not me. I shouldn't have done that. I hope he's OK and I hope he gets better."
He also apologized in a postgame tweet.
I don't have any intentions to hurt anyone when I play football. I didn't mean to hurt Vontez Burfict, I just wanted to throw a block for my teammate. I apologize for standing over him and that isn't me. Praying he gets better.— JuJu Smith-Schuster (@TeamJuJu) December 5, 2017
After the game, Brown yelled "karma" repeatedly.
Asked if that comment was related to Burfict, Brown said, "I ain't talking about nobody. Karma is karma. Karma is in life. You do the wrong things, you get the wrong things out of it."