Lying just six seconds behind Majka after stage 5, the New Zealander's time of 28 minutes and 45 seconds, only 18 seconds behind stage winner Dibben, was more than enough to secure the race lead.
The last rider out on the road, overnight leader Rafal Majka (Bora-hansgrohe) rolled through after 29 minutes and 26 seconds and now sits second on GC, 35 seconds adrift.
The Kiwi rider couldn't quite believe he now wears the yellow jersey:
Majka could not hide his disappointment or his ambition for the future.
"My legs were not perfect today," he said. "I tried everything and I pushed as hard as I could but it was my first ITT of the year.
"I still need to do more training on my TT bike because I want to win these races. To be honest, I am disappointed but still second place (on GC) is a good result."
Andrew Talansky (Cannondale-Drapac) finished third on today's stage which sees him just one second behind Majka. A fast ride from American Brent Bookwalter (BMC) saw him finish just seven seconds behind Dibben and nudged him up to fourth on GC.
It was an impressive ride from stage winner Dibben, the 23-year-old's first WorldTour win.
But it was a horrible day for Australia's Lachlan Morton who experienced difficulty with his drive train on the start ramp which cost him more than a minute and ultimately the young rider's classification lead.