MP Conor McGinn says his constituency - which includes Haydock, Billinge and Garswood - stands to lose £3.8m if Britain leaves Europe.
The Labour MP cited figures produced by the Stronger In campaign calculating the amount poured into the borough from EU coffers.
And the report says the area would have to forfeit a similar amount every year if the country votes for Brexit.
It also says that during the 2007-2013 European Structural Funds programme, the North West received £990 million and will receive £910 million under the 2014-2020 programme which has been allocated to Local Enterprise Partnerships who will help decide how the money is spent locally.
Mr McGinn, MP for St Helens North, said: “This analysis by the Stronger In campaign shows just how important remaining in the EU is for people in St Helens North and across the North West.
“St Helens North benefits through receiving EU funding, which supports regional development, provides investment in businesses, creates job opportunities, improves prospects for young people through apprenticeships and higher education.
“Northern Trust and Morley Estates have received over £1.2m and £2.5m respectively for important projects run in the constituency. Being in Europe supports jobs and lower prices here at home.”