On the biggest stage, against the world's finest attack, with the number one Test ranking at stake, the Yorkshireman showed maturity and confidence to rise to the challenge and keep his head after the other frontline batsmen had come and gone.
He fell agonisingly short of what would have been a richly deserved and hugely popular maiden Test century, and the standing ovation he received would still have been scant consolation.
But there was no doubt that Bairstow vindicated his selection and, by extension, ensured that Kevin Pietersen's omission would not remain the focus of attention at Lord's.
Inevitably, there were those ready to criticise the 22-year-old for the way that he faltered and floundered from 85-95, but that is utterly churlish in the context of what was a very impressive innings.
Bairstow battled through several spells of hostile fast bowling from the tourists to compile the highest score of the match so far, and in so doing, showed his team-mates the application and discipline that is required to accompany talent against the Proteas' attack.
Having had some weakness against the short ball exploited by West Indies' fast bowlers, he came into this match with many questions to answer about his technique and temperament - and a giant KP-sized void to fill in the middle order.
Pietersen was, of course, the man-of-the-match at Headingley, but Bairstow did not appear to be shouldering any of those burdens as he continued his fine innings, albeit falling just short of the landmark he was so keen to reach.
Bairstow lost confidence after his experience against West Indies, but he judged the line of his off stump so wisely and with such impeccable judgement that he was an assured presence at the crease, unmoved by any of the pressure that the tourists were striving to build.
In the build-up to this final Test, Bairstow sought the counsel of his close friend and mentor Geoffrey Boycott, while also working intensively with England batting coaches Graham Gooch and Graham Thorpe.
A century against Australia A last week provided the perfect reassurance as to his form and refined technique, and he has not looked back since then.
The match remains very much in the balance with the irrepressible Hashim Amla at the crease and looking ominous for the tourists, but there is plenty of work left to do for both sides over the next two days.
It may even be that it comes down to Bairstow to deliver for England once more under enormous pressure in the second innings.
The 22-year-old has already proved his worth to Andrew Strauss's side and, despite not having a maiden Test century to celebrate with an isotonic this evening, he can now feel as though he is deserving of his place at number six.
STAT OF THE DAY: As his score went to 90, Bairstow overtook his father David's Test runs total of 125. Simon Jones and Ryan Sidebottom managed this filial achievement at Lord's in 2004 and 2001, but both in their first Test innings.
TWEET OF THE DAY: "Stat of the day: the England player to have hit the most sixes in Tests under Andy Flower is Graeme Swann." (@TheCricketGeek)
QUOTE OF THE DAY: India's elegant middle-order batsman VVS Laxman announced his retirement after a brilliant career. "It's been 16 years since I made my international debut for India and I feel it's the right time for me to move on," he said. "I have always kept the country's success and needs ahead of my personal aspirations and I would have loved to contribute to the team's success especially against England and Australia later in the season. I think it's the right time to give opportunity to a youngster in home conditions before the tough overseas tours next year."
- Sports & Recreation