After making an excellent birdie on the par five 18th look completely routine, he walked off the 18th green and was asked how it all felt.
"This is what I've been working for," he said. "It's been a difficult few months for me, only my family know what is going on. I can't believe it."
As he faced the press following his victory, the immensely likeable 24-year-old was more than happy to open up - and the cause of his torment will have been relatable to many in a 2020 that has been like no other year.
The coronavirus pandemic, that saw MacIntyre's native Scotland go into lockdown in the early part of the year and led to there being no European Tour events for four months, affected the mental health of many around the world - and professional golfers were not immune.
"The first nine, ten weeks was fine," he said. "I had things to do - I was trying to lose weight, become stronger, I had set myself goals. I was doing it alongside another person from my area and we were on Peloton almost every day, so there was a target.
"When that finished, there was nothing for us to do. I was like, 'I'm wasting time, I'm wasting away here' and I just started to struggle.
"But everyone knows that my family are right behind me and the support that I get from them is huge. I spoke to my mum and she guided me in the right directions.
"I went to see Paul, a psychologist, who has helped me, helped me in a huge way. I was coming down the stretch there just knowing what to do - just take your time and be yourself."
He added: "I struggled mentally from about eight, ten weeks after lockdown, almost when it opened up slightly - it felt like you were getting released into the open but you were still getting told what to do and that was tough for me."
Up until lockdown, golf had appeared anything but tough for MacIntyre, who secured three second places and four further top tens in 2019 en route to finishing 11th on the Race to Dubai and claiming the Sir Henry Cotton Rookie of the Year Award.
A top ten at his first event of the 2020 season in Dubai looked to signal a continuation of that form but during lockdown, there were moments of doubt.
"It was in the back of my mind that I’d lost my game a little bit," he said. "When I put work in, I know my game will come back.
"I didn’t have the motivation for a wee while, I wasn’t wanting to play golf and wasn’t enjoying it. I finally got the bug back and it’s what happens. You start practising more, enjoying it, you could see the smile on my face last week, never mind this week.
"Mike was giving good chat, everything was good and we’re finally back to where we’re meant to be."
Mike is Mike Thomson, a fellow Scotsman and former caddie of Brooks Koepka who has recently come onto the bag and was doing another job when MacIntyre came calling.
"I felt like I needed a change of some sort when my mind wasn’t quite right," said MacIntyre.
"Personally said to Stoddy (manager, Iain Stoddart) can we sound him out - working another job - to see if he would come back.
"He said he’d be interested. So when Iain told me that I picked up the phone and said ‘what’s happening? When can you start?'.
"I feel like he’s got the winning mentality that I was wanting, we’re not scared to take on the world - and he’s certainly not. He’s been a brilliant help and today it showed at the end."
After a stunning start to his European career and a tough summer, Robert MacIntyre has a new caddie, his old outlook back and a trophy in the cabinet.
Take on the world? Why not, Bob.