The droid, who is stolen from police and reprogrammed, stars alongside Dev Patel, Hugh Jackman and Sigourney Weaver in the dystopian romp, which took in $13.3 million, according to box office tracker Exhibitor Relations. (READ: 'Chappie' review: Unexplored possibilities)
The film kicked last weekend's top earner, con-artist flick Focus, into second place. The dark comedy, starring Will Smith as a crook who takes on a protege played by Margot Robbie, raked in $10 million.
Debuting in third with $8.6 million was sequel The Second Best Exotic Marigold Hotel, featuring an all-star, if aging, cast including Judi Dench, Maggie Smith, Bill Nighy, Penelope Wilton and Richard Gere.
The tale of retirees staying in an expanding hotel in Jaipur, India, also stars Dev Patel as the facility's manager, in his second weekend box office debut.
Falling to fourth was British spy film Kingsman: The Secret Service with $8.3 million, while children's animated romp The SpongeBob Movie: Sponge Out of Water trailed behind with $7 million.
Racy bondage tale Fifty Shades of Grey, which saw a record February opening, meanwhile slid into sixth place.
The erotic tale of billionaire Christian Grey (Jamie Dornan) and his sadomasochistic relationship with college graduate Anastasia Steele (Dakota Johnson) took in $5.6 million.
Kevin Costner sport drama McFarland, USA, the story of a small-town cross-country team made of students from immigrant families, was in seventh place with $5.3 million in its third week out.
Landing in eighth with $5.1 million was horror flick The Lazarus Effect, about medical students who discover a way to bring people back to life.
Teen comedy The Duff fell one spot to ninth, pulling in $4.9 million.
And Vince Vaughn comedy Unfinished Business debuted to the tune of $4.8 million, in tenth. –Rappler.com