The Children's Society said the pandemic had a significant toll on children’s wellbeing and left them more exposed to problems at home.
Hampshire had 8,905 children in need on March 31 this year, up 4% from 8,561 a year before.
It was also up 7% on the 8,293 children in March 2020, who were largely identified before the pandemic.
The rate of children in need in Hampshire was 312 per 10,000 children this year, below England's overall rate of 334 per 10,000.
The recent figures are from the Department of Education's annual children in need census, which includes unborn children and young people on social care and protection plans, those looked after by local authorities, disabled children, and young people over the age of 18 still receiving support from children's services.
There were 27,374 referrals made during the year to March 2022 in the area. When a child is referred to children’s social care services, an assessment is then carried out to identify the primary need for services.
A total of 27,661 assessments were carried out in Hampshire, with 2,769 finding the child was not in need.
Primary needs for social care services in the area included family dysfunction – making up 67% of cases where an assessment identified a need. At 22%, abuse or neglect was also a significant need.
On March 31 this year, 1,024 child protection plans were in place for children who were considered to be at risk of harm.
Sarah Wayman, The Children's Society head of policy and research, added the increased number of children needing social care services is therefore "no surprise".
Ms Wayman said: "At The Children’s Society, we have seen through our practice and research how successive lockdowns left many children feeling more worried about everything from Covid to missing school, exams, friends and their future."
"All this takes its toll on children’s wellbeing and can lead to mental health conditions like anxiety and depression and we have seen evidence of that in our frontline services," she added.
"Lockdowns also meant some children may have been left more exposed to problems at home, with little respite from challenges and risks there."
England had 404,310 children in need at the end of March, up 4.5% from 2021 and up 3.9% from 2020.
The Department of Education said the return to in-person classes after Covid-19 restrictions was likely to have contributed to the increase, with 650,270 referrals made last year.
A spokesperson from the department added: "It is vital that children are safe and supported in orderfor them to thrive, no matter their background."
They said the department is "strengthening links" between social care and education to keep the vulnerable children and young people engaged in education alongside providing funding for pupils with social workers or in care.