Potential victims as young as 12 were uncovered by the county council-commissioned investigation into child sexual exploitation (CSE).
Of the 51 children identified, 14 were considered at "significant" risk.
There have been several CSE arrests in the county, and some abuse has been "disrupted", the report said.
The potential victims were all female, with the exception of two cases.
The majority identified in the report were aged 14 or 15, but the youngest was 12.
Dorset County Council said it would discuss the report's findings with a view to taking earlier intervention in future.
Source: Dorset County Council
Det Insp Neil Phillips, of Dorset Police, said the force wanted to "educate and safeguard" those at risk.
A number of children in local authority care go missing and are at risk of CSE, he said, but there are also abused children who live at home with parents and carers.
"It's down to children being inquisitive, pushing boundaries and exploring," he said.
"Some children will experiment with alcohol and drugs and come into contact with adult males that are slightly older than them that are willing to try and exploit them sexually."
Duncan Stanway, from Barnardos, described the report as "really worrying and shocking" but said he was encouraged the council had recognised the problem.
"For too long lots of local authorities have brushed child sexual exploitation under the carpet," he said.
Children from a wide range of social backgrounds were exploited, he said, but more vulnerable groups, such as those in care or young people who have run away from home, were most at risk.
More than 50 vulnerable children were at risk of being sexually abused in Dorset over the past year, a report has revealed.