12 overs.
In the next over, left-arm spinner Zohaib Khan removed Shahid Afridi (15), caught by Imran Junior. Afridi struck one six from 17 balls.
Fawad Alam (19) and Sarfraz (47*) then added 36 off 24 balls for the sixth wicket.
Fawad, who was caught by Imran Khan Senior off his own bowling, smashed one six and one four from 13 balls.
Sarfraz stayed till the end and hammered six fours from just 26 deliveries.
Imran Khan Junior (3-26) took important wickets of Khalid Latif, Asad Shafiq and Anwar Ali to end as leading wicket-taker of the event with 16 scalps.
Imran Khan Senior ably backed him with 2-35 in four overs.
This was the fifth time in the domestic T20 history that Karachi lost in the final.
In the second semi-final, on Monday night, Peshawar overwhelmed Sialkot by five wickets thanks to Rafatullah Mohmand’s explosive fifty.
Rafat smashed 51-ball 78 with five sixes and six fours to enable Peshawar to chase down the 170-run target with eight balls to spare.
The experienced first-class cricketer added 109 for the third wicket with Mohammad Rizwan, who smacked unbeaten 32-ball 47, in which he hit four fours and a superb six over square-leg.
Young pacer Ammad Butt took 2-36.
Sialkot had to face tough time before posting a fighting total in the end. After Shoaib Malik (1) failed to click, his younger brother Adeel Malik took responsibility and struck unbeaten 70 off 46 deliveries to take his side to a decent total.
Adeel struck seven fours and three sixes. He dominated the 62-run sixth wicket stand with Shakeel Ansar, who belted 14-ball 20 with two sixes.
Mukhtar Ahmed (34) and Bilal Asif (20) had scored 38 off 20 balls to provide a solid base to their team.
Mukhtar hit four fours and a six from 24 deliveries. Bilal smashed one six and one four from 14 balls.
Imran Khan Junior picked 2-34 in four overs.
Score Board
Peshawar won toss
Karachi Blues
Khurram Manzoor run out 41
Shahzaib Hasan c Adil Amin b Imran Khan 0
Khalid Latif c & b Imran Khan (1) 23
Asad Shafiq c M Rizwan b Imran Khan (1) 19
Shahid Afridi c Imran Khan (1) b Zohaib Khan 15
Fawad Alam c & b Imran Khan 19
*†Sarfraz Ahmed not out 47
Anwar Ali c & b Imran Khan (1) 7
Rumman Raees run out 0
Salman Zaib not out 0
Extras (lb 1, w 4, nb 1) 6
Total (8 wickets; 20 overs) 177
Did not bat: Abdul Ameer
Fall: 1-1, 2-53, 3-83, 4-95, 5-105, 6-141, 7-168, 8-173
Bowling: Imran Khan 4-0-35-2 (1nb, 2w); Taj Wali 3-0-39-0 (1w); Imran Khan (1) 4-0-26-3; Zohaib Khan 4-0-38-1 (1w); Iftikhar Ahmed 2-0-17-0; Adil Amin 3-0-21-0
Peshawar
Rafatullah Mohmand c Salman Zaib b Anwar Ali 43
Israrullah c Rumman Raees b Abdul Ameer 9
Iftikhar Ahmed not out 57
Musadiq Ahmed lbw b Shahid Afridi 4
†M Rizwan not out 58
Extras (lb 1, w 4, nb 2) 7
Total (3 wickets; 18.5 overs) 178
Did not bat: M Fayyaz, *Zohaib Khan, Adil Amin, Imran Khan (1), Imran Khan, Taj Wali
Fall: 1-48, 2-55, 3-68
Bowling: Anwar Ali 4-0-34-1 (1w); Rumman Raees 3-0-33-0; Abdul Ameer 3.5-0-39-1 (1w); Shahid Afridi 4-0-21-1; Salman Zaib 4-0-50-0 (2nb, 2w)
Result: Peshawar won by 7 wickets
Series: Peshawar won the National T20 Cup
Twenty20 debut: Salman Zaib (Karachi Blues)
Umpires: Ahsan Raza and Shozab Raza. TV umpire: Ahmed Shahab. Match referee: Mussadaq Rasool