The 24-year-old has been a Lions train-on player for three seasons and plays for Wilston Grange in the QAFLW. She joins the club replacing Olivia Lacy, who will miss the 2026 season with a thigh injury.
Matenga models her game on Lions player Dayne Zorko and is a small running defender with clean skills who is versatile and can be used in a number of positions.
Brisbane Lions AFLW senior coach Craig Starcevich said Matenga's story is a real show of perseverance.
"This is Keys' third season as a train-on, and she's been playing some strong football in the state league, so it's a great example of what can happen if you keep it up," Starcevich said.
"Whenever Keys has come in and played trial games with us, she's shown she can play at the same pace as our players.
"She is able to compete at our level really well because of her speed and running ability."
Matenga said that it has been a huge journey getting to this spot.
"I just feel like if I show up and do what I can with what I have, everything will fall in place.
"I'm super stoked with the opportunity, to have a chance and give it a go and hopefully get a game.
The 2026 NAB AFLW season kicks off in less than two weeks, with Brisbane taking on Essendon at Windy Hill on Sunday, August 16.
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