The winners dug out the win well, particularly as they were reduced to 14 men when Mikey Conway earned a second yellow card for a sliding tackle in the 51st minute.
Offaly did have a chance of sending the game into extra-time when Shane Connolly fouled Paul McPadden but Niall McNamee dragged the penalty wide.
Johnston deserved to be on the winning side after a glittering performance and was pleased to have people asking him about football again having been at the centre of the most contested transfer in GAA history.
Sensibly though, knowing more than most about the vagaries of sport, he is keeping his feet very firmly on the ground.
“Ah sure you’re completely reliant on the ball coming in” said Johnston. “The lads did a brilliant job around the middle and we got enough scores to get us through. It’s Dublin now and it’ll be good to get another game before the league starts.”
He didn’t enjoy being the focus of such a negative media spotlight but is pleased to be back doing what he enjoys best.
“I wasn’t talking about it. Everybody else was talking about it. A lot of stuff is out of your control. It’s difficult to control what other people thought. People have their opinions; I can’t control that.
“You just keep working hard and knuckle down and hopefully good things will come. All you can do is try your best.
“It’s not hard to integrate with those lads. They’re not just good footballers, they’re very good people.”
Offaly had the better of the early exchanges, getting off to a perfect start when Eoin Carroll sent a low shot to the Kildare net after three minutes.
They were good value for their four-point lead when Alan Mulhall’s failure to gather Padraig O’Neill’s long ball was compounded by Paul McConway picking the ball off the ground and conceding a penalty.
Conway slotted coolly to the right corner in the 28th minute and Johnston followed up quickly with his third point – and first of four from play – to bring the sides level.
It was 1-4 apiece at the break but Kildare opened up a two-point lead soon after the resumption thanks to Cathal McNally and Johnston.
Offaly kept in touch though and two points from McNamee restored parity once more with 20 minutes still remaining.
Kildare’s response to that, and Conway’s dismissal, was impressive. With O’Neill in particularly getting through a mountain of work, they got themselves two clear again thanks to Johnston and it was three when McNamee had his late chance from the spot.
He couldn’t convert though so it was Johnston and Kildare’s day.
Scorers for Kildare: S Johnston 0-7(3fs); M Conway 1-0(pen); E O’Flaherty 0-2; P O’Neill, C McNally, E Bolton 0-1 each
OFFALY: N McNamee 0-6(5fs); E Carroll 1-0; A Sullivan, P Cunningham, D Kelly 0-1 each
KILDARE: S Connolly; O Lyons, M Foley, H McGrillen; E Bolton, M Conway, E O’Flaherty; G White, P O’Neill; M O’Flaherty, C McNally, B Flanagan; D Flynn, T O’Connor, S Johnson.
Subs: J Byrne for McNally (53); R Kelly for E O’Flaherty (55); P Brophy for O’Connor (66); R Sweeney for Bolton (70)
OFFALY: A Mulhall; S Pender, S Sullivan, P McConway; D Hanlon, B Darby, D Kelly; A McNamee, R Brady; G Guilfoyle, B Connor, A Carroll; M Mitchell, N McNamee, A Sullivan.
Subs: P Cunningham for Mitchell (40); E Rigney for McConway (42); P McPadden for Carroll (65); M Young for A McNamee (67)
Referee: J Curley (Meath).