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.
A 14-year-old girl has been charged with the murder of a promising teenage footballer described as a "role model" for his community.
Junior Nkwelle, 15, was stabbed to death outside a block of flats on the Loughborough Estate in Brixton, south London, on Thursday evening.
He was pronounced dead at the scene, with police saying the killing was not believed to be gang-related.
The girl, who cannot be named for legal reasons, will appear at Camberwell Green Youth Court on Monday, a spokesman for the Metropolitan Police said.
A 16-year-old boy who was arrested on suspicion of murder remains in custody at a south London police station.
A 14-year-old girl has been arrested on suspicion of murder after a 15-year-old boy was stabbed in Brixton, south London, on Thursday evening.
15-year-old Junior Nkwelle was a promising young footballer and police have said the killing was not gang-related.