Mr Corbyn received 124 votes, compared with 64 for Mr Smith, in a meeting held at Hounslow Civic Centre on Wednesday (August 10) evening.
Salman Shaheen, of the pro-Corbyn Momentum group, said the result would have been even more emphatic had newer members received an invite earlier after a ruling preventing them from voting was overturned in court.
"I think this result represents the national sentiment within the party towards Mr Corbyn," he said.
'Corbyn will be elected with an even stronger mandate'
"I think he will be elected with an even stronger mandate this time. The parliamentary Labour Party really needs to fall in behind him so we have a united party to take on the Conservatives."
Constituency meetings were previously prohibited during the leadership contest, but getwestlondon reported how Corbyn supporters in Hounslow defied the ban by meeting at a local pub.
Ruth Cadbury, the Labour MP for Brentford and Isleworth, is backing Mr Smith in the leadership contest.
In a letter to constituents explaining her reasons, she questioned Mr Corbyn's leadership skills and his prospects of steering the party to victory in a general election.
She said he was costing the party the support of "ordinary voters" and Labour's results at the last local elections were the worst ever under an incoming opposition leader.
"For every Green supporter and non-voter Jeremy attracts to Labour he loses the support of several ordinary voters, as those of us who have been meeting local voters in recent weeks and months can confirm," she wrote.
'Majority of trade union members want a change in leadership'
"That's why a majority of trade union members, for example, want to see a change in leadership...
"Polls consistently show that we are now down to our core vote at best, and that will never be enough to win an election and certainly not for this seat to remain Labour."
Mr Shaheen claimed Labour's electoral record under Mr Corbyn had been "impressive", including "numerous" by-election successes and a convincing victory for new London mayor Sadiq Khan.
He said it was no surprise the party had "taken a hit" in the polls given the infighting which was distracting MPs from taking on the Conservatives.
He added that he had a "great deal of respect" for Ms Cadbury, and called on her to get behind Mr Corbyn to help Labour win the next general election.
Councillor Theo Dennison, chairman of the Brentford and Isleworth CLP, said 1,946 constituency party members were invited to vote on Wednesday in what he described as a "good-humoured" meeting.
Ballot papers for the Labour leadership contest are due to be delivered later this month, and the result is set to be announced on September 24.