The service for Liam Curry, 19, and Chloe Rutherford, 17, is taking place at St Hilda's Church in South Shields.
The couple's families have asked people attending to wear pink and blue for the funeral.
The teenagers, who were described as "inseparable", were among the 22 people killed in the terror attack on the Ariana Grande concert last month.
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Chloe was studying music at college and was about to start an apprenticeship in travel.
Graeme Brett, owner of Westoe Travel in South Shields where she worked part-time, said: "She was a lovely, bubbly girl.
"The photograph you saw of her smiling, that's just her."
He added: "Liam would come and pick her up after work - he was always there early waiting for her.
"The two of them were always together, very close, he was a lovely lad.
"They were always such a perfect couple."
Mr Curry, a former pupil of Gateshead College, was studying for a degree in sport and exercise science at Northumbria University.
His father, Andrew Curry, died aged 49 in March after being diagnosed with cancer.
Liam had raised money for the Sir Bobby Robson Foundation, which funds cancer research, since he was 14.
A foundation spokeswoman said: "Liam was an outstanding young man and a great credit to his family."