According to unofficial overnight ratings figures, 'Jamie's American Road Trip' pulled in 13.4% of the available viewers in its 9pm timeslot.
A further 300,000 people watched when it was shown on Channel 4+1.
In the first episode in the series Oliver spent time in Los Angeles' Mexican community, learning recipes which immigrants had brought from their homeland and finding out how cooking programmes are helping young people to escape from gang life.
The show has been heavily promoted on Channel 4.
'Jamie's American Road Trip' was ahead in the ratings of the new series of BBC Two's hit 'The Choir', which was watched by 2.5m, or 10.8% of the audience. However, both lagged behind ITV1 in the 9pm slot, which showed 'The Fixer', and BBC One's 'Traffic Cops'.
'The Fixer' drew an average audience of 3.8m while 3.6m tuned in to BBC One to find out what traffic police in South Wales get up to.
'Jamie's American Road Trip' was sandwiched between two episodes of 'Big Brother' on Channel 4, including a surprise eviction in the 10pm show.
With just three more days left of the 10th series from 'Big Brother', almost 2.6m tuned in to see shaven-headed Lisa evicted from the house.
Last week Channel 4 confirmed that the next series of 'Big Brother' will be the last it screens, although producers Endemol are confident it will be taken up by another broadcaster.
Earlier in the evening, 'EastEnders' pulled in an average of almost 6m on BBC1 at 7.30pm, while ITV1's 'Emmerdale' had 5.8m viewers at 7pm.
Five's most popular show was 'CSI: Miami' at 9pm, with 2.1m tuning in, representing 9% of the available audience.
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