The series is becoming a coming-of-age story for Bouchier, aged 25, who had previously found it difficult to secure a permanent place in England's highly competitive batting line-up.
She was promoted to open from number three after scoring 43 and a 47-ball 71 in the first and third T20s respectively. Sophia Dunkley, who was out of form, was moved down to number seven.
England made a watchful start to their innings, with Danni Wyatt returning from the Women's Premier League in India to replace Tammy Beaumont and form a new opening partnership.
Wyatt scored nine runs and became England's leading T20 run-scorer. They reached 35-1 after the six-over powerplay.
Bouchier gained confidence and played powerfully with innovative reverse ramps and sweeps. She was also impressively quick between the wickets despite suffering a leg injury during the middle overs.
Alice Capsey and Sciver-Brunt returned from the WPL. While Capsey was quite scratchy for her 25 from 32 balls, Sciver-Brunt made the most of the platform set by Bouchier with an entertaining stand of 35 from 14 balls with Knight.
The captain's rapid innings, with a strike-rate of 150 across the four T20s, is a positive boost for England. It shows that she has improved and adapted her game in the shortest format to suit head coach Jon Lewis' aggressive style of play.