Campaigners say faster, more frequent trains would bring 70,000 new jobs to the region in the next 20 years.
Ashley Rogers, chairman of north Wales' business council, said improvements would play a "key role" in boosting the economy.
The campaign calls for electrification, better rolling-stock and the doubling of services on some lines.
Businesses representing 300,000 people from Cheshire, Mersey Dee and north Wales have backed the Growth Track 360 campaign.
Many hope rail improvements will reduce traffic on the A55 and create better connections to the rest of the UK.
Employers such as Siemens, based in Llanberis and Moneypenny in Wrexham, are among the backers.
Mr Rogers said: "Improved infrastructure has a key role to play in ensuring this vision becomes reality - opening up opportunities, attracting talented, skilled people from across the UK and helping the region to capitalise on its intrinsic strengths and grow and develop."
About 75% of large businesses, who responded to the campaign, hope the improvements will deliver time savings, while 64% of small businesses want to see better access to customers.
Martin Gray, finance director at Siemens, said high quality transport links were essential to ensure access to key talent across the region.
Rachel Clacher, director of Moneypenny, who want to grow their workforce from 500 to 1,000 over the next three years, said better connectivity was crucial.
The Growth Track 360 campaign was launched by the north Wales and Mersey Dee rail taskforce, which represents enterprise zones, local authorities and businesses across Cheshire, north Wales and Merseyside.
Earlier this year the Welsh Government, backed by north Wales' businesses, submitted a business case to the Department for Transport (Dft) for cash to electrify the line between Crewe and Holyhead.
They hope to secure Â£800m from the DfT to upgrade the 105 miles of track within the 2019-2024 funding period.
More than 400 companies have backed calls for improvements to rail services in north Wales.