Firefighters have formed a guard of honour to farewell volunteer Andrew O'Dwyer, who has been remembered as a proud NSW Rural Fire Service member whose greatest achievement was his young daughter.

Mr O'Dwyer, 36, died in December when his fire truck rolled while battling the large Green Wattle Creek blaze southwest of Sydney.

"You need to know that your dad was a selfless man, he was a special man, and he only left us because he's a hero," RFS commissioner Shane Fitzsimmons told Charlotte O'Dwyer during his eulogy at a requiem mass for her father on Tuesday.

"There are no words that can adequately describe our sorrow, our respect, our regard, for the loss of Andrew … in that tragic accident."

Wearing a white dress with her hair in pigtails, one-year-old Charlotte at one stage touched her father's casket before wandering up to the pulpit at Our Lady of Victories church in Horsley Park, the suburb where his RFS brigade is based.

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Inset: Andrew's cherished daughter Charlotte at her father's casket. Photo: ABC

Hundreds of family, friends and RFS members filled the church – still decorated for Christmas – as tributes flowed for the young father.

Prime Minister Scott Morrison, NSW Premier Gladys Berejiklian, state Emergency Services Minister David Elliott and federal Labor MP and local member Chris Bowen were among the mourners.

Volunteer Geoffrey Keaton, 32, was killed in the same crash and was remembered at a separate service last week.

RFS volunteers and representatives from other emergency service agencies formed a guard of honour as Mr O'Dwyer's casket was carried into the church, with some saluting and others placing their hand on their heart.

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Inset: Prime Minister Scott Morrison hugs Horsley Park RFS captain Darren Nation at the funeral. Photo: ABC

Church bells tolled as Mr Fitzsimmons presented a commendation for extraordinary service to Mr O'Dwyer's partner Melissa.

Mr O'Dwyer's father Errol said farewelling his son was the hardest thing he had ever done and described his son as a free spirit who lived in the moment.

His greatest achievement came "with the birth of his daughter Charlotte, the apple of her father's eye"," Errol said.

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Inset: A haka is performed at Andrew's funeral. Photo: ABC

"Although my heart is broken, you have made me very proud," he said.

Members of the Maori community performed a haka outside the church following the service as a sign of respect, before Mr O'Dwyer's casket was driven away. It's understood his best friend is Maori.

Mr Morrison, who attended with wife Jenny, gave a long hug to Melissa.