Kelechi Iheanacho marked his Celtic debut in stunning fashion, scoring a 96th-minute penalty to send the champions back to the top of the Scottish Premiership on goal difference.
The Nigerian striker kept his composure from the spot after VAR confirmed Lewis Mayo had handled James Forrest’s effort inside the box.
Iheanacho’s precise strike sparked jubilant scenes among Celtic supporters at Rugby Park.
Earlier, Daizen Maeda had given Brendan Rodgers’ side the lead with a diving header from Marcelo Saracchi’s cross shortly after half-time.
Kilmarnock responded quickly, David Watson rising highest to nod in an equaliser that appeared enough to secure a valuable point for the hosts.
The contest was scrappy for long spells, though new Celtic signing Sebastian Tounekti impressed with his pace and flair on debut.
The decisive moment, however, arrived deep into stoppage time when Iheanacho seized the spotlight.
The victory lifted Celtic level on points with Hearts but ahead on goal difference after five matches.
Kilmarnock remain on four points, sitting eighth in the standings.
For Iheanacho, the goal carried extra meaning.
His career had stalled after a disappointing season at Sevilla, where he struggled for form and saw his contract terminated in the summer.
A reunion with Rodgers, who once guided him at Leicester City, now offers the chance of a revival.
His dramatic debut suggests Celtic may be the perfect stage for his resurgence.
