Fresh off a humbling 4-2 defeat to powerhouses Germany and without Arsenal star Steph Catley (managed), Australia got their World Cup preparations back on track in Chambly, France on Tuesday (Wednesday AEDT).
McKenna was the spark, as she produced two classy first-half strikes before an own goal by Haiti defender Kethna Louis, and goals to Caitlin Foord, Daniela Galic, Clare Wheeler and Holly McNamara completed the victory.
The Nottingham Forest midfielder has now secured three goals in four national team apparances, adding a selection headache for coach Joe Montemurro.
When the Matildas mentor was asked if he thought his team was ready for next year's World Cup, he laughed and said "no".
"We need time ... It's probably more about selecting the squad because now we're starting to build a big roster of players, and I need more time to make a decision on who I can bring," Montemurro said.
"It was a good window for us. We played against Germany ... We felt that we were not far, and we know the areas where we need to fix."
Along with McKenna, the Australians midfield produced a masterclass as Alana Murphy dispatched a crafty pass to set up Galic while Wheeler had an assist and goal.
"I was a spectator in 2023, and I loved watching the group. It only made me hungrier to want to be a part of it," McKenna said.
"So to be in a position to potentially be selected is amazing.
"I'm loving it (the Matildas) so far. There's obviously a lot of talent. It's great exposure for myself and (I'm) just growing."
Questions had loomed over captain and star striker Sam Kerr's fitness after she complained of ankle soreness following the German clash, but she was also influential, playing a big role in two of the goals.
The rousing victory helped the Matildas firmly keep their No.15 world ranking, which currently puts them in pot two out of four for the World Cup draw, meaning a mathematically better chance for a more favourable draw.
It wasn't a smooth-sailing win for Montemurro's players though, as their first-half defence looked timid when their Caribbean opponents employed their counterattack, but they utterly dominated the second half as Haiti's wheels fell off.
It took just 80 seconds for the Matildas to draw first blood when Wheeler cut the ball back to McKenna, who produced a sublime one-touch strike into the roof of the net.
But moments later, Haitian midfield star Melchie Dumornay tucked the ball into the bottom right corner to equalise.
On the stroke of halftime, McKenna re-established the Australians' lead when she pounced on a loose ball in the box and buried it in the bottom left corner.
In the 53rd minute, Foord poked the ball to Kerr, who steered it goalwards and found the foot of Louis.
The sparkling Foord-Kerr combination wreaked havoc again when the Arsenal winger scored before substitute Galic found her first international goal.
Wheeler added her name to the scoresheet when her cross bound for Foord snuck into the bottom left corner before McNamara iced the game.
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