The 46-year-old appeared on stage to present an award with 51-year-old Piers to a mix of cheers and boos.
Piers had his mouth taped up, and once the cameras screened a close up, the audience went wild with excitement.
"It's been a controversial week on Good Morning Britain," said Susanna.
"We've had tears, we've had tantrums, we've even had a walk out.
NTAs 2017: Piers Morgan 'finally gagged' by Good Morning Britain co-host Susanna Reid
I've done what people have been urging me to do for quite some time, I have finally gagged Piers Morgan!
"So I've done what people have been urging me to do for quite some time, I have finally gagged Piers Morgan!"
He then gestured for Susanna to hurry up and continue, but the daytime host was having none of it.
"Just enjoying this moment," she told her co-presenter before pausing once more.
One viewer tweeted: "#NTAS that's the best I've seen @piersmorgan look – suits you!"
NTAs 2017: Piers Morgan gagged by Good Morning Britain co-host Susanna Reid
Inside the National Television Awards 2017
Wed, January 25, 2017
All the winners from the 2017 NTA's
1 of 66
Mary Berry reacts to winning the Best TV Judge during the National Television Awards
"Very deserving win for Mary Berry and The Chase! Nice to see Piers Morgan gagged – I feel sorry for Susanna #NTAS," posted another.
A third disagreed with the joke, adding: "To make a 'Panto villain' of him is actually quite disarming and dangerous. The s***e he spouts is far more serious than that #NTAs2017."
"So glad they've got Piers Morgan's mouth taped up on the NTAs. Piers Morgan has finally been silenced #NTAS," wrote a fourth.