Thomas, who has started the season in outstanding fashion for Town, beat off competition from Fulham striker Aleksander Mitrovic, Cardiff City defender Aden Flint and QPR centre-half Rob Dickie.
The London-born player, 22, qualifies for Wales via his mother from Newport.
The former Boreham Wood wingman, who provided four assists and a goal in August, said: said: “I’m absolutely delighted to win this award,
"I would like to thank all my team-mates, and the members of staff that we work with every day on the training ground.
"They helped me prepare for the new Sky Bet Championship season and hit the ground running and I am very grateful to them.
"Now my challenge is to maintain this form as we head into the rest of the season, and I am determined to keep improving.
"My aim is to keep performing, keep helping Huddersfield Town get points on the board and hopefully push into the Wales squad too.”
Town head coach Carlos Corberán, who missed out for the manager's accolade, with the gong going to Fulham chief Marco Silva, added: “Sorba’s achievement says a lot about the level of football in England.
"He was playing in the National League one year ago, and now he is having a very good impact in the Sky Bet Championship.
"This is unique to England, and not uncommon when you think of examples like Jamie Vardy, Michail Antonio, Chris Smalling and many more.
"It shows that everyone can have the dream of playing in the highest levels of football in England.
"Sorba deserves a lot of credit for his performances, which come from his mentality.
"He has shown a very good balance in having confidence in his ability, and in the level of demand he puts on himself.
"You will not be successful if you have too much of one and not enough of another."
It is the first time that a Town player has received the monthly award since James Vaughan in August 2013.
Sheffield Wednesday goalkeeper Bailey Peacock-Farrell and Bradford City striker Andy Cook both missed out on player accolades in League One and League Two respectively.