A fleet of new ambulances, costing £16m, is to be announced by the Welsh health minister on a visit to Anglesey.
A former chief executive said the service was "dangerous"
The new chief executive of the Wales Ambulance Trust last month said the service needed £140m long term investment, including new vehicles.
The funding will pay for 119 new ambulances and 67 other patient vehicles over the next few months.
A public inquiry into the service, described as "in crisis" by a previous chief executive, is still ongoing.
Health minister Dr Brian Gibbons, who is visiting an ambulance station in Llangefni, said: "We've heard many times over recent months that the ambulance service in Wales needs to modernise.
"This funding is a first step towards seeing that modernisation happen."
Dr Gibbons said the trust was working through a plan which would ensure "that the men and women who provide this important service are supported by a modern organisation and that performance and response times of the ambulances can improve to meet all our expectations".
Mr Murray said the dedication of staff has been "inspiring"
The ambulances will be equipped with the latest life-saving equipment, which some of the current vehicles lack.
Ambulance trust chief executive Alan Murray said the investment would "ensure that its vehicles are more efficient and fitted with the latest medical equipment to provide the care patients need".
Mr Murray started work in August after months of turmoil for the service.
Acting chief executive Roger Thayne resigned in May after just two months in the post, claiming the organisation was in "crisis".
He wrote a damning report cataloguing outdated equipment, a history of poor management and delays in ambulances reaching patients, which he said contributed to a "dangerous" service.
The inquiry by Wales' auditor general is due to report by the end of the year.