Jenna, 15, disappeared on 10 September from the village of Abersychan, near Pontypool.
Jenna's stepfather, 36-year-old Mike Baldwin, was arrested in connection with her disappearance six weeks after she went missing and later charged with her murder.
Her body was eventually found off a mountain road in a shallow grave.
A service celebrating Jenna's life was held at Trinity Methodist Church in High Street, Abersychan, at 1300 GMT, before a burial at Panteg cemetery.
Grave
The teenager's family has announced the headstone on her grave will bear her birth father's surname.
Jenna's mother Desiree Baldwin, 39, said the headstone will be inscribed with the name Jenna Brookfield.
Her father Nigel Brookfield, 42, who lives in Abergavenny, was among the chief mourners at the funeral.
"
I wanted a special send-off for Jenna. She sometimes talked about death and what she wanted
"
Desiree Baldwin
Jenna's white coffin was covered in red roses and was taken by hearse from Mrs Baldwin's home in Pontnewynydd to Trinity Methodist Church in Abersychan.
Her schoolfriends attended wearing bright colours and the teenager's favourite pop songs were played as a special tribute.
Jenna's school, Abersychan Comprehensive School, was closed to years 10 and 11 for the funeral.
Pupils travelled from the school by coach to attend the service.
Mrs Baldwin has spoken of her wish to celebrate Jenna's life during the service.
She said: "I wanted a special send-off for Jenna. She sometimes talked about death and what she wanted.
"Everyone who wants to come will be welcomed."
However, she requested that no filming take place inside the church during the service.
Chief Inspector John Oliver of Gwent Police, who led the search for Jenna, said: "Our thoughts are with Desiree Baldwin and her family.
"Gwent Police are continuing to provide support and we sincerely hope that the family will be able to start rebuilding their shattered lives."