The survey found around 11 million UK adults have injured their back, neck, hips, knees, wrists or another part of their bodies while working or schooling from home during lockdown.
Only one in three (32%) workers report having a dedicated workspace in their home.
Instead, homeworkers are improvising, with 18% working from a sofa or armchair, 17% from a dining or kitchen chair, 12% from bed and 5% from a beanbag.
As a result, 24% of homeworkers report being often hunched over while they work, 18% say they slouch or slump, 23% are balancing their computer on their legs or a chair arm, and 21% sit with their back or legs twisted.
Damian McClelland, clinical director for musculoskeletal services at Bupa UK Insurance, said: “When social distancing measures were introduced, many workers were thrust into working from home to keep them safe, with little time to prepare their workspaces.
“So it’s concerning, but perhaps not surprising, to see that so many are now struggling with their musculoskeletal health.”
Additionally, the study shows that younger people are disproportionately affected, reporting the highest levels of neck, hip, knee and wrist pain.
Only 26% of workers aged 18-34 report having a simple desk and a chair with a backrest, compared with 30% of those aged 35-54 and 33% of those 55 and older.
Workers aged 18-34 are also twice as likely to work from their bed as their older counterparts, with 18% doing so, compared to 9% of 35-54-year-olds.
Just 11% of UK workers in pain at home have sought medical help, with the majority using over-the-counter painkillers, massages or ice baths.
More than a quarter (28%) have done nothing to relieve their symptoms, risking longer-term damage - particularly as two in five (42%) homeworkers intend to continue working from home when social distancing measures are lifted.
McClelland added: “As we move towards the ‘new normal’ where higher levels of working from home are likely to feature, it’s really important to address any pain or discomfort now, to make this sustainable in the long term.
He said HR could recommend simple changes such as ditching the beds and beanbags and sitting up with feet on the ground.
“Workers should adopt hands-free sets for long phone calls and make time to stretch, even if that’s doing yoga at your desk which can go a long way towards preventing strain.
“Seeking help for long-term and persistent pain remains essential. Early diagnosis and access to treatment can have a positive effect on the long-term prognosis of musculoskeletal conditions.”