Kelly, who is eligible for the mini-draft designed to help the Giants build their list, ran a time of 9min 48sec, which ranks in the top five in the history of the combine, on the final day of proceedings at Etihad Stadium.
The strong performance came on the back of a 14.6 beep test and repeat sprint time of 24.91sec, which placed him inside the top five runners at the combine in both categories.
"Josh has really pushed himself up with a brilliant performance," AFL national talent manager Kevin Sheehan said.
"He's got great skills and we saw him put up the best time today. I think he's going to be a star in the AFL."
WA pair Jack Martin and Jesse Hogan have long been considered the frontrunners to be taken in the same manner that Gold Coast picked up Jaeger O'Meara and Adelaide secured Brad Crouch at last year's mini-draft.
But Kelly has given AFL recruiters food for thought with his eye-catching display at the combine, where he also placed inside the top 10 in the Brad Johnson goalkicking test, which was introduced this year.
"I try to work on [my endurance] because I'm not the biggest framed body, so I've got to use that as one of my strengths out on the footy field," Kelly said.
"I've spoken to a couple of clubs this week [who were] just telling me to make the most of my opportunities. If it doesn't turn out [with the mini-draft] this year then I can bounce back harder next year."
Murray Bushrangers defender Tom Clurey followed up his combine-best beep test result of 15.1 with a time of 10min 01sec to finish second with North Ballarat's Dom Barry third in 10min 09sec.
The 3km time trial was the final act of a gruelling four days of testing for 115 AFL hopefuls, which Sheehan said would form an important part of the clubs' preparation for the NAB AFL Draft in November.
"We'll now put all these results up for the clubs ... and they'll form their own views," he said.
"They'll also go back to the video tapes of the blokes playing the game as well. [The combine], I'd say, is the last 15 per cent of the [player] analysis as the clubs get ready for the 22nd of November."
3KM TIME TRIAL TOP 10:
Josh Kelly - 9min 48sec
Tom Clurey - 10min 01sec
Dom Barry - 10min 09sec
Kamdyn McIntosh - 10min 14sec
Jake Neade - 10min 16sec
Sean Hurley - 10min 17sec
Tanner Smith - 10min 18sec
Sam Siggins - 10min 19sec
Mitchell Van Den Berg - 10min 19sec
Sean Lynch - 10min 20sec
Jesse Hogan - 10min 20sec
