He is just 16, and with only four goals in the Championship to his name, but Arsenal are prepared to pay £12m for him.
Walcott has scored five goals in nine games for England's under-17s
And Walcott's former coach at Southampton, Simon Clifford, believes the striker can become just as good as Wayne Rooney, his predecessor as England's best teenager.
And indeed also as good as Thierry Henry, who could soon be his Gunners strike partner.
Here Clifford gives BBC Sport his assessment of Walcott.
I was aware of Theo before I started working at Southampton, but that had been from watching him on video.
So what struck me immediately was just how hard he could strike a football.
I've never seen a player hit a ball like Theo - so much power, so much accuracy, with the minimum of back-lift.
Last season he had already had a lot of publicity due to his FA Youth Cup performances - Real Madrid, Chelsea and Manchester United were all supposedly interested in him.
Given that level of interest what I particularly liked about him was how humble he was.
I introduced training sessions for early in the morning and late in the evening that Theo took part in.
He then broke into the first-team and Harry Redknapp didn't want him to do extra sessions, but he would still come along and help me put out the cones and be with his friends.
People talk about his pace, but what also impressed me was his desire to get forward as quickly as possible.
If there is any opportunity to go forward he will do it rather than play the ball back.
Theo is surrounded by wonderful people. He has got a great family as well as good advisors. That will be really important.
What is important to remember is that Theo is the product of the English academy system.
I like the timing of his runs, his determined attitude, the fact that he can play in different positions up front and that he is calm in front of goal
Arsenal boss Arsene Wenger
He is a very quick, lively player who has come on the scene and really brightened the landscape
Ex-Saints coach Dave Bassett
The kid can run through puddles and not make a splash - he drifts over the ground
Ex-Saints boss Harry Redknapp
The likes of Theo and Wayne Rooney come through in spite rather than because of the system.
The English academy system is one where players are training for just four hours a week.
Compare that to Ronaldinho when he was a 16-year-old with Gremio where he would have been training for up to 20 hours a week.
I think Walcott is going to the right club in Arsenal.
You only have to look at the way Thierry Henry has developed since he was reunited with Arsene Wenger after they had first worked together at Monaco.
As for weaknesses, Theo needs to know where to position himself when he hasn't got the ball, but I'm sure that will come as he is still very young.
His defensive side needs to be worked on, but obviously that is not why Arsenal are buying him.
In joining Arsenal he will come up against defenders who are just as quick as himself.
Then he will have to learn that he will not be able to rely just on his pace and he will have to find creative ways of getting past defenders by passing and dribbling.
It is a big challenge because Henry is probably one of the top three players in the world but it is possible for Theo to get to the level of Henry.
I would also not be surprised if Theo broke into the England team in a year's time - he is very much the type of player who can rise to the occasion.