After telling Will that his film, Hancock, was "sick" and asking what the actor's own favourite role had been, one young fan blurted out 'you rock!' and got a little more than he probably could have dreamed of...
80 young people from 40 London schools, who had gathered to celebrate their end of term achievements, could hardly believe their eyes when Will Smith walked onto the stage.
Speaking to our reporter Clare Fernyhough at City Hall today, Will Smith, with son Jaden, said how important it is for young people to have positive role models.
Boris Johnson tweeted this picture of him with Hollywood legend Will Smith saying 'great to see Will Smith, @officialjaden & 90 kids at my Leadership Club achievement events today.'
Hollywood star Will Smith gave a group of Brixton schoolchildren a day to remember, when he appeared in front of their morning assembly. Ria Chatterjee reports.
Actor Will Smith offered some words of advice, as he addressed teenagers at a school in Tulse Hill.
This video posted on Youtube - and shot by Will Smith himself - shows school-girls in Lambeth going wild for their Hollywood visitor.
The Hollywood star - famous for roles in The Fresh Prince of Bel-Air and Men in Black - met students at St Martin-in-the-Fields High School for Girls in Tulse Hill, doing a question and answer session and signing autographs.
Labour MP Chuka Umunna has given Will Smith a tour of Lambeth today, saying that the Hollywood star wanted to see the "real London".
The pair called into a music venue and a coffee shop in Brixton before taking questions from students at St Martin-in-the-Fields High School for Girls in Tulse Hill.