Crews reached 58.7% of Category A emergency calls within eight minutes in April, up from 52.9% in March. The target is 65%.
The most serious emergencies - so-called Red 1 - saw 71% of ambulances arriving within eight minutes.
Welsh Ambulance Service chief executive Tracy Myhill called the figures "very encouraging".
"Our aim is to continue our improvement and remain focused on delivering excellent clinical care to the people that need our help," she added.
Of the 35,162 calls received in April, 13,120 were deemed serious and life-threatening.
Ms Myhill said they still wanted the public to help by only using the service appropriately.
"We still get called far too often to calls that do not need a Welsh Ambulance Service response," she said.
Ambulance response times have improved for the fourth month in a row, according to the latest figures.