Meg Lanning followed a century in Australia’s series-levelling win in Bristol on Thursday with another key contribution as she made 85 from 89 balls at New Road.
Ellyse Perry provided support with 67 from 58 balls as Australia posted a total of 241 for seven.
Perry then dealt a huge blow to England’s run chase by dismissing Charlotte Edwards and Sarah Taylor in her first two overs.
England never really recovered, succumbing tamely to 152 all out and a defeat that leaves them 4-2 down in the multi-format Ashes – although there are 10 points still to play for, starting with the Test at Canterbury next week.
The win also lifts Australia five points clear at the top of the ICC Women’s World Championship, and seven ahead of England who remain in fourth – with only the top four teams securing automatic qualification to the 2017 World Cup.
England had chosen to bowl first after Sunday’s rain forced the match into the reserve day, but the hosts made a key mistake when they failed to take advantage of a mix-up between Lanning and Nicole Bolton that left Australia’s captain stranded.
Instead of reducing Australia to 49 for two, England had to wait until the 27th over before their next breakthrough.
Alyssa Healy joined Lanning to step up the pace in a third-wicket stand of 31, but it was when Perry joined her captain that the real damage was done.
They put on 85 in 13 overs, with Lanning enjoying a second life when Lydia Greenway could not hold a sharp chance at point off Katherine Brunt.
Lanning was denied a second consecutive century, but Perry powered on to take her tally for the series to 193 at an average of 64.
She then underlined her all-round value by having Edwards caught behind from the fourth ball of the England innings, a wicket which proved a hammer blow to the hosts’ hopes.