First-choice Test wicket-keeper Bairstow was only told he was playing by England coach Trevor Bayliss just over half an hour before the start of Thursday's (Sept 1) match after regular one-day gloveman Jos Buttler suffered a hamstring injury in the warm-up.
Bairstow responded with an assured display behind the stumps. He then made a brisk 61 and helped Ben Stokes (69) add 103 for the fifth wicket as England, who had stumbled to 72 for four chasing a target of 248, eventually won by four wickets to go 4-0 up in this five-match series.
Last year Bairstow guided England to a one-day series clinching win over New Zealand -- a key-staging post in their recovery from a dismal first-round exit at the 2015 World Cup -- with an unbeaten 83 at Chester-le-Street after Buttler was ruled out with a hand injury.
There has been talk of England, the hosts of both the 2017 Champions Trophy and 2019 World Cup one-day tournaments, playing both Buttler and Bairstow in the same white-ball side, with one of them featuring as a specialist batsman.
But in the meantime Bairstow, who has already scored nearly 1,000 runs in Test cricket this year, is desperate to make the most of any one-day chances he gets, however late they come.
"It was about 32 minutes before the start," Bairstow said after being asked when he knew he was playing in front of his adoring Yorkshire public yesterday.
"Trev came over and just said, 'You're in'." However, with England on the up in one-day cricket, Bairstow wants to be more than a white-ball 'reserve'.
"It's a special group of players and we believe we can go a long way in world competitions and series," he said.
"But naturally I'm frustrated not to be in that XI week in week out. "Every time I get an opportunity I want to try to impress and that's all I can do.
"Whether that be keeping wicket, just playing as a batter, batting at one or 11 -- every time you go out there you try to do your best.
"You've just got to take it on the chin, crack on and hope you take the opportunity when it does come along," added Bairstow ahead of Sunday's series finale in Cardiff.
Bairstow, the son of late former Yorkshire and England wicket-keeper David Bairstow, looked considerably younger than his 26 years yesterday, having shaved off his beard after receiving a message from his mother, Janet, a Headingley administrator.
"I got told off by my Mum," said Jonny. "My Grandma had been on the phone."