Proceedings commenced at noon, with the street closed off to host a performance by the marching band from Ohio State University.
Top players from the Jacksonville Jaguars and Buffalo Bills took to a branded NFL stage for interviews throughout the day, and cheerleaders representing the Buffalo Bills team delivered a performance on stage.
Attendees could take part in a range of interactive activities at the NFL Lab, including field goal kicking and quarterback challenges. A mini football field with an NFL Play 60 zone was also created for children.
Agency Wasserman Experience delivered the event, and it is also behind the fan zones around each of the games.
The Jacksonville Jaguars played against Buffalo Bills yesterday (25 October), with the latter taking out the match. Those who attended the game were similarly entertained by a marching band and cheerleaders, meanwhile NFL-focused activities were available to take part in.
The final UK game in the 2015 International Series will take place on Sunday (1 November) when the Kansas City Chiefs play the Detroit Lions.
The Regent Street takeover is now in its third year. Last year's event saw appearances from the Miami Dolphins and Oakland Raiders.