The 30-year-old frontman knows boss Derek McInnes from their time together at Bristol City.
And he has decided to join up with his former manager once more at Pittodrie after leaving MK Dons earlier this summer.
Maynard has penned a one-year deal after joining up with the Dons at their St Andrews training camp to undergo a medical.
"He's a player I've worked with before and I'm delighted he's joined the club
I was keen to add more goal threat to the team and I'm sure Nicky will give us that."
The former Arsenal trainee, who has also turned out for Crewe, West Ham and Cardiff, becomes the Reds' fourth new signing of the summer following the captures of Greg Tansey, Ryan Christie and Greg Stewart
McInnes is hopeful he will land at least another new face before tonight's 11pm registration deadline as he gears up for Thursday's opening qualifying clash with Bosnian outfit Siroki Brijeg
However, he will be able to add another 'wild card' recruit to his squad before 11pm on Wednesday
Source : PA