The youngster came off the bench in the Carabao Cup tie to rescue the Gunners from a morale-sapping defeat, scoring twice and sending Arsenal through in the process.
Nketiah, who has scored nine goals in 20 appearances for the club's Under-23 team, and 15 goals in 16 outings for the Under-18s, subsequently became the first player born after Arsene Wenger's appointment to score for Arsenal.
Henry immediately took to Twitter to praise the 18-year-old, though he was not shocked to see him settling into life in the first-team so quickly.
What a night for @EddieNketiah9 . So happy for him and not surprised at all!— Thierry Henry (@ThierryHenry) October 24, 2017
Nketiah has played for England at both Under-18 and Under-19 level, scoring seven goals in total for his country across both age groups.
Jack Wilshere was another to express his delight at seeing the youngster take centre stage at the Emirates Stadium.
He posted on Twitter: "Good to be in the hat for the next round. Well done to Eddie Nketiah different class mate. Thanks to the fans also, kept us going."