After almost an 80-minute hearing on Tuesday, the judiciary panel comprising Penrith great Tony Puletua, former referee Paul Simpkins and chair Geoffrey Bellew SC took 20 minutes to reach their decision.
The five-eighth, who joins South Sydney next season, will learn the length of his ban shortly when the panel returns to announce the sentence.
The match review committee referred Wighton directly to the judiciary after he was placed on report just after half-time of the Knights' 30-28 win in Newcastle on Sunday.
Gamble's forearm was wrapped around Wighton's chin while attempting a tackle, after which Gamble immediately claimed to referee Ashley Klein he had been bitten.
Klein told the bunker he had seen a row of bite marks on Gamble's forearm but opted against sending Wighton from the field, instead placing him on report.
Wighton entered a not-guilty plea and appeared via video link before the judiciary. He was supported by Raiders football manager Matt Ford and chief executive Don Furner.
Wighton's counsel Nick Ghabar did not dispute contact had been made with Gamble's forearm.
But the five-eighth claimed Gamble had applied "extreme" pressure to the back of his head and his face in wrapping his arm around him in the tackle.
"His forearm actually fell into my mouth before I could even close it," Wighton said.
"I've got no alternative, nowhere to go. It was full body weight, full pressure (on my head).
"My mouth was jammed open, not at one stage did I clench, not one little bit."
The case of NRL counsel Patrick Knowles hinged on the suggestion there had not been any more pressure applied than in any standard NRL tackle. Wighton didn't like the claim.
"How many games of rugby league have you played?" he retorted before being reprimanded by Bellew.
Knowles suggested that mere pressure alone would not have created such a clear indentation on Gamble's forearm and there was an intent to bite.
He said given Wighton's airways were not blocked by Gamble's arm, he was not in such danger that a bite was necessary.
Ghabar said no intent to bite could be proven, insisting the six camera angles of the incident did not show a tightening of Wighton's facial muscles that would be consistent with a bite.
Gamble opted against testifying before the panel to keep his schedule clear ahead of Saturday's semi-final against the Warriors.
Ghabar suggested Gamble not giving evidence and Klein opting not to send Wighton from the field both cast doubt over the legitimacy of the biting accusation.
But Bellew discouraged the panel from giving weight to those claims.
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