Workers from the Southern Focus Trust, which ran hostels in the city and helped the homeless, waved placards and chanted as bosses went to their annual meeting in the New Theatre Royal in Guildhall Walk.
Union members were demanding a 2.75 per cent pay rise in line with inflation and dismissed offers of two per cent or less.
Paul Buking, senior union representative for the parent Portsmouth Housing Association, said 95 workers out of 169 staff were taking action to demand fairer pay rewards.
He said: ‘We only had around 50 members at the start of this dispute – and that figure has almost doubled now.
‘Our support is getting stronger by the day.
‘I am disgusted by the whole thing – all we want is 2.75 per cent to keep up with the cost of living. It’s insulting,’ he added.
Southern Focus Trust Unison representative Colin Levine said: ‘Our staff are carers not trouble-makers.’