The wicketkeeper-batsman hit a quickfire 23 to set up Kolkata's chase of 160 as they hammered Sunrisers Hyderabad by eight wickets on Tuesday in Ahmedabad.
It was the 22-year-old's first outing in this edition of the world's richest cricket competition, having made the heart-wrenching decision to leave his ailing mother.
He answered the SOS call from his team after Phil Salt left to prepare for England's T20 World Cup campaign.
"My mum is still sick. I went there (back to Afghanistan)," Gurbaz told reporters.
"I got a call from KKR once Phil Salt was leaving. They called me and messaged me saying, 'Gurbaz, we need you. What is your situation?'
"I said I'll come."
Gurbaz joined two-time champions Kolkata ahead of last season but has been a bit-part player.
He flew home to be with his mother, but returned when his team needed him most.
"My mother is still recovering in the hospital, I speak to her every day," he said.
"But I knew my KKR is also my family. They needed me here, so I came back from Afghanistan.
"It's hard, it's tough, but I have to manage."
The glovesman took two catches as Hyderabad were bowled out for 159 with pace ace Mitchell Starc returning figures of 3-34.
He then hit a 14-ball knock laced with two fours and two sixes to set the pace for Kolkata's chase in 13.4 overs and their entry into their fourth IPL final.
"As a cricketer you know what to do," he said.
"If you do not have an opportunity, you should prepare well and be ready. Whenever you get a chance, you have to be ready."
Despite limited playing time in the IPL, Gurbaz has played 55 times for Afghanistan in T20s and is set to be a key member at the World Cup next month.
Most of the Afghan players are already in the West Indies for the tournament but Gurbaz said his focus is on the IPL final and his "first priority is KKR".
The final is on Sunday in Chennai.
Hyderabad will have another shot on Friday at making the decider when they clash with the winner of Wednesday's game between Rajasthan Royals and Royal Challengers Bengaluru.
