Winning by a long-neck, Mr Brightside edged out Queensland visitor Antino ($8) with the Chris Waller-trained Fangirl ($5) the same margin away in third.
"He really is our flag bearer," Will Hayes added.
"We owe this horse everything. He started our momentum as a stable and really generated a lot of hype for us and the way he's raced today, it was heart-in-your- mouth stuff.
"We took a risk and put the blinkers on, back in trip, it was suitable and Craig rode him terrifically."
"The grand final was the Cox Plate," Craig Williams said.
"He ran fourth but ran a phenomenal race. They've come here today for the Champions Mile, with all these horses, they've gone for blinkers for the first time and he was the right product today."
Race favourite Pride Of Jenni ($4.80) led as expected but faded to run last with rider Ben Melham reporting that the mare bled from both nostrils.
On her Pride Of Jenni's racing future, Ciaron Maher said: "If she was to have been retired at any of her last 10 starts she has still done a phenomenal job."