Smith picked up a Golden Globe nomination for the role

The tale of a father and son who become homeless, which features Smith opposite his own son Jaden, took an estimated $27m (�13.8m) in its first weekend.

Second place went to fantasy Eragon, followed by a live action version of the children's novel Charlotte's Web.

Last week's number one, Mel Gibson's epic Apocalypto, fell to sixth place.

The Pursuit of Happyness is the latest in a long line of number one films at the box office for rapper-turned-actor Smith, whose previous hits include Men In Black and Independence Day.

'Best friend'

NORTH AMERICAN BOX OFFICE 1. The Pursuit of Happyness ($27m) 2. Eragon ($23.45m) 3. Charlotte's Web ($12m) 4.Happy Feet ($8.5m) 5. The Holiday ($8.2m) 6. Apocalypto ($7.7m) 7. Blood Diamond ($6.3m) 8. Casino Royale ($5.7m) 9. The Nativity Story ($4.7m) 10. Unaccompanied Minors ($3.7m) Source: Exhibitor Relations

"Audiences around the world love him," said Rory Bruer, head of distribution at Sony Pictures.

"Everyone who sees Will Smith or meets Will Smith feels like he could be their best friend," he said.

"He has that type of charisma that resonates throughout, whatever room he's in."

The 38-year-old star was shortlisted for best actor in a drama at the Golden Globes on Thursday, and is widely touted to pick up his second Oscar nomination for the role.

Eragon, based on a novel by teenager Christopher Paolini about a farm boy and his flying dragon, took $23.4m (�11.9m).

Charlotte's Web, which mixes live action and animation and features the voices of Julia Roberts, Robert Redford and Oprah Winfrey made a more modest $12m (�6.1m).

Musical opening

But its distributor, Paramount, says it expects the film to follow the pattern of family movies such as Stuart Little, which started slowly but attracted consistent audiences over the holiday period.

"The movie has every chance to get to $100 million off of this opening," said Don Harris, executive vice president of distribution at Paramount.

Paramount also opened the acclaimed musical Dreamgirls, which stars R&B star Beyonce, on 21 screens in New York, Los Angeles and San Francisco.

The film made an unusually high total of $360,000 (�184,000), partly because of a promotional ticket price of $25 (�12.78).