The centre-back has also been fined 50,000 pounds following a disciplinary hearing.
The sanction stems from Romero's red card in Tottenham's 2-1 Premier League defeat to Liverpool on 20 December. The Argentine defender was shown a second yellow card in stoppage time for kicking out at Liverpool's Ibrahima Konate, having previously been booked in the 66th minute for dissent. Romero did not leave the field promptly after the dismissal and reportedly argued with referee John Brooks, prompting the FA to charge him with acting improperly.
Romero admitted the charge, and an independent regulatory commission confirmed the one-match ban and fine. He had already served the automatic suspension for the red card, missing Spurs' 1-0 victory over Crystal Palace on 28 December. Prior to that, he had also been sidelined for Spurs' 2-1 loss to Fulham on 29 November due to yellow card accumulation.
In a statement, the FA said the written reasons for the latest sanctions will be published in due course. Spurs have opted not to appeal the decision.
Spurs manager Thomas Frank defended his captain, describing Romero as a "young leader" who made a mistake. He and the club's sporting director, Johan Lange, met with Romero to discuss the incident. Meanwhile, Romero apologised to fans on social media, noting that players should not bear the brunt of supporters' frustrations.
With Tottenham currently 14th in the Premier League and winless in their last three games, the team will look to bounce back against Aston Villa in the FA Cup.
Manchester City produced a ruthless FA Cup performance as they demolished League One Exeter City 10-1 in the third round, with debut goals from Antoine Semenyo and Ryan McAidoo on a remarkable afternoon at the Etihad.
Eddie Howe has admitted Newcastle had work to do in the FA Cup ahead of Saturday's third-round clash with Bournemouth, confirming rotation and updating on club captain Jamaal Lascelles.
Pep Guardiola insists Manchester City will take the FA Cup seriously, and will not rest all his first-team players because they need to find a win.
Thomas Frank has vowed Tottenham would "go full strength, all in" for the FA Cup as he looked to change the mood around the club ahead of today's Aston Villa's visit to the Tottenham Hotspur Stadium.
