the most watched sport worldwide is soccer because soccer is EVERYWHERE on earth and the world cup every 4 years is watched EVERYWHERE so soccer is your answer
soccerActually I believe the current most watch sport "on TV" is Formula 1 Racing. 527 million people watched F1 in 2010
the world cup
The Super Bowl
Soccer, the world cup mainly.
I would say basketball or football
Football with ver 25 million viewers every week
The Most Watched Sports in the UK is Football, only because you cant get away from it, its always on the TV, the second most watched sport at the moment is Cricket when Football is not on that is, but if you would like to know what the second most popular sport is. well its Hockey ("Field") after Football that is but unfortunately it is hardly on the TV at all and Rubgy, Cricket is probably in the top 5