Mr Browne, 28, was attacked during a night out with friends in the Co Tyrone town on Saturday.
He was taken to hospital with severe injuries but died on Monday.
Members of the Castlederg and Strabane communities gathered at the Diamond in Castlederg town square, where a lorry that belonged to Mr Browne was set up.
In the back of the lorry was a picture of the father-of-one in a large heart surrounded by lights.
Parish priest Father Paul Fraser spoke to the crowd and Mr Browne’s family, who attended virtually.
Fr Fraser said the community was united in sorrow with his family.
“The outpouring of grief that has been evident in our community over these past couple of days bears witness to how much Conor Browne was loved,” he said.
“We have felt overwhelmed by sadness and loss. Shocked indeed that such a thing could happen in our wee town, that happened in the small hours of Saturday morning, the tragic events unfolded just a few steps from where we’re standing.
“Our sense of shock and loss is nothing compared to what’s being felt by Conor’s family.
“This evening we gather to send a message of love and support to his parents Geraldine and Matt, his son Cobie, his sisters Sinead and Grace, and his brothers Seamus and Andrew and the whole family circle of Brownes and Collins, and we want them to know that as a community we are united with them in sorrow.
“Conor was a friend to everyone and we want his friends to remember Conor and his smile and that hopefully will help them over the pain of what they witnessed here on Saturday morning.
“While Conor was fighting for his life in hospital in Belfast the whole community here in Castlederg and Aghyaran and beyond stormed heaven with prayers for Conor and his family.
“We prayed for one thing, that Conor would survive and recover. It wasn’t to be.”
A minute’s silence was held and the service ended as Fast Car by Luke Combs was played, a song Fr Fraser said was one of Mr Browne’s favourites.
SDLP MLA for West Tyrone Daniel McCrossan said it was an “extremely difficult” day for the community.
“You can feel it here in Castlederg, the community are united in their condemnation of all violence,” he said.
“This was a brutal, terrible act that has claimed the life of a young man and left devastating and profound consequences for his child and for his family, and indeed for the many people who knew and loved him in this community and beyond.
“From social media, you can see that he is very widely loved and well known, and the consequences of what has occurred here in recent days has hit this community very, very hard and first and foremost, my thoughts and prayers are with his family at this time and his friends.”
Mr McCrossan said that Mr Browne’s death would have “rippling consequences”, but that Castlederg is a safe town.
“It is a hugely shocking thing and the rippling consequences of it have reached many places but I would like to reassure people that it is no reflection of this area,” he said.
“This is a good decent, hard-working, quiet, tight-knit community. And this one act, although very terrible, is no reflection of daily life here.
“This is a safe place, but certainly in the aftermath of what has happened there will need to be conversations with the PSNI, community workers, to see how we can better protect people at night in our town centres.
“But certainly I would like to reassure people that Castlederg is a good place to do business to shop, to live. It’s safe. It’s a tight knit community.”
Before the vigil floral tributes were placed at the site where Mr Browne was killed.
The organisers of the event, Darkness into Light Castlederg, said in a post that Mr Browne’s death had sent a dark cloud over the community.
“Our town of Castlederg was sent into a sense of shock, disbelief, anger and sorrow over the last few days. The news that broke yesterday that Conor had passed away has put a dark cloud over our town,” the post read.
“Conor was a much loved Father, Son, Brother, Uncle, Cousin and a brilliant friend to so many people. Conor’s death has affected everyone who had the pleasure of knowing this great fella and it has affected people whom never had the privilege of meeting him.
“We as a community want to show our support and solidarity to Conor’s immediate family and to the Browne and Collins family circle.
“We want to let the people know that all the good work that has been done in our town is not going to be undone by this vile act.”