Former Bafana Bafana defender Carnell took his side to the top of the regular season standings in Major League Soccer in what proved a record year for the club.
Union topped the Eastern Conference by a single point from Cincinnati. They won 20 of their 34 games with six draws and eight defeats, the most number of victories for the club in a single campaign.
Carnell’s side claimed the Supporters’ Shield for the club who were the best in the regular season.
He has also steered them through the first hurdle in the post-season play-offs as they defeated Chicago Fire and now await the winner of the tie between Charlotte and New York City in the next round.
“It’s not just about me, it’s about the club,” Carnell was quoted by Delaware County Daily Times. “But through the club doing well, I’m doing excellent in terms of my personal gains and personal achievements. So it’s almost a thought process and a shift in the thought process.
"Instead of putting me first, you put the team first, but it’s me that gets rewarded.”
He found out he had won the award at a team meeting when messages from loved ones were shown.
“I saw my wife pop up on the screen,” Carnell said. “So it was pretty cool. She had left a nice message, and some folks from South Africa reached out. So, really special moment, for sure.”
Carnell played for South African at the 2002 World Cup but spent most of his playing days in the German Bundesliga.
He was previously assistant coach at top South African club Orlando Pirates.