He added Canada earlier this year when he won at the Calgary Stampede in a short transatlantic hop from the UK where he had mounted his successful bid to retain his place in the Scotland team for next July's World Championships in France, and in July threw a warning of World title hopes when he won the Royal Welsh All Nations final.
With fastest time and best quality points on Saturday, Mutch won a six-man Open final, featuring one Australian, by 6.85pts over runner-up Jack Fagan, of Te Kuiti.
Defending champion Mark Grainger, also of Te Kuiti, was third.
Mutch shore the 20 sheep in 19min 43sec, almost 40 seconds ahead of second-man-off Ethan Pankhurst, based in Australia but whose history includes the 2015 Golden Shears Senior title in home-town Masterton.
Hayden Tapp, of Taihape was fourth, Pankhurst, penalised heavily by judges monitoring the quality, had to settle for fifth, and home show hope and Warrnambool-Te Kuiti partnership stalwart Roger Mifsud was sixth, unable to match the visitors for pace in an event which has been dominated by New Zealand shearers over the years.
Mutch was also to the fore in the surprisingly dominant Te Kuiti transtasman challenge victory, with Warrnambool traditionally favoured in the Austalian leg of the annual home-and-away contests of eight sheep each — including four merinos.
The Australian trio of Glenn Stephens, Tryson Scholz and Mifsud were 1, 2, and in the race, Stephens at 12min 38sec finishing more than a minute and a half before anyone else, and 2min 25sec before quickest Kiwi shearer Fagan.
Times indicated it was tougher than usual, but quality was the winner as the Kiwis turned it round big-time with a win by 19.4pts, compared with the Australian team's win by almost 11 points last year.
There was more success for the Kiwis, with Napier shearer Ricci Stevens adding the Senior title to the New Zealand championships Senior title he won at Te Kuiti in April.
His final, over eight sheep each, was bereft of Australian competitors, with four from New Zealand and two from Wales.