Button's fourth victory in five grand prix saw him lap world champion Lewis Hamilton who finished just out of the points in ninth.
The race netted a 35.8% share of the 12.15pm-3.15pm audience and viewing peaked at 4.9m in the 2.30pm-2.45pm time slot.
BBC One also ruled the evening ratings with its detective drama 'Inspector George Gently' winning the primetime slot with 5.3m viewers and a 20.8% share of the 9pm-10pm audience.
Last night's episode saw Gently and Bacchus investigating the death of a woman who was stabbed in the head and left perfectly posed on a church altar.
The second instalment of ITV1's 'Martin Clunes: Islands of Britain', featuring Clunes attending a coronation ceremony on Piel Island and emptying buckets of beer over the new king's head, pulled in 4.1m viewers and a 16.3% share.
Five's terrestrial premiere of 'The Da Vinci Code', starring Tom Hanks as the Harvard professor Robert Langdon caught up in an unusual Parisian murder case, drew 3.7m viewers and a 16.2% share of the 8pm-10.45pm audience.
This was Five's best movie performance since 'Men in Back II' in 2006, which attracted 3.9m viewers.
Channel 4's 'The Secret Millionaire', featuring Roisin Isaacs who made her fortune in the healthcare industry, scored 2.2m viewers and an 8.6% share of the 9pm-10pm audience. Including Channel 4+1 figures it reached 2.5m viewers.
The first part of BBC Two's 'South Pacific' documentary series, featuring a slow-motion shot of the back of a big wave from underwater, won 2.3m viewers and a 9% share of the audience.
On Saturday night 'Britain's Got Talent' improved on last week's ratings of 10.5m. It was up to 11.1m viewers, giving it a 48.2% share of the audience.
ITV1 repeated its outperformance of BBC One, starting from the early evening with 'All Star Mr & Mrs' at 6.15pm-7.15pm, which was up against 'Robin Hood' at 6.15-7pm.
The ITV1 show delivered 4.5m viewers, a 26.5% share, against 'Robin Hood''s 3.3m and 19.4% share.
BBC One improved with variety show 'Tonight's the Night' at 7pm-8pm, which got 4.2m and a 22.1% share despite a poor first quarter-hour because of the clash with the end of 'All Star Mr & Mrs'.
The rest of the BBC One show was neck and neck with ITV1's 'Primeval', which ran at 7.15pm-8.15pm and managed 4.9m viewers and a 25.1% share.
On BBC One 'The National Lottery: 1 vs 100' mustered 4.3m viewers up against 'Britain's Got Talent', after which BBC One finally gained the lead with 'Casualty' starting at 9.15pm.
The hospital drama brought in 5.3m viewers, a 23.8% share, to the 4.3m (19.8%) that ITV1 got for 'ITV's Best Ever Ads' at 9.15pm-10.15pm.
As usual on a Saturday night there was little competition from the other terrestrial channels. BBC Two's 2.6m audience for a 'Dad's Army' repeat was the biggest among them, giving the channel a 13.2% share at 7.30pm-8pm.
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