The USA Test star has been key to Northampton Saints' quick-fire start to the season both in Aviva Premiership Rugby and Europe.
Aviva Ambassador Austin Healey said: "Samu Manoa has been exceptional this month. His destructive defence has become the norm, but his ball-carrying around the fringes of both lineouts and rucks has been one of the key factors in Northampton Saints' success.
"He constantly makes extra yards and not just through his size but also excellent footwork as we saw against Saracens.”
The award is judged on the performances of Aviva Premiership Rugby players in all competitions.
CLICK HERE to see a great video of Manoa in action in October.
Manoa beat Saints lock Courtney Lawes and Exeter Chiefs flanker Tom Johnson to the second Aviva Premiership Rugby Player of the Month title of the season after they were shortlisted by a prestigious media panel.
BT Sport pundit Healey believes that Manoa has quickly become one of Aviva Premiership Rugby's most cherished overseas signings and will be pivotal to Northampton's quest for silverware this season.
Healey added: "For me he has been one of, if not the outstanding signings of recent years and his shear bulk mixed with fantastic rugby ability adds to the Saints’ hopes that this season could be the one when the bridesmaids become the bride.”
Manoa wins a trophy from title sponsor Aviva and £250 to donate to a charity of his choice.
The winner was voted for by a panel of media professionals – Nick Mullins (BT Sport), Alastair Eykyn (BT Sport), Mick Cleary (Daily Telegraph), Ian Stafford (Mail on Sunday), Jill Douglas (ITV Sport), Chris Jones (Radio 5 Live), David Rogers (Getty Images) and Ben Coles (Planet Rugby). The panel was chaired by Paul Morgan, Premiership Rugby's Communication Director.