The Airbus H145 is the first of two that are to replace the charity's current ageing aircraft.
The new helicopter can fly at night has exceptional flight performance and lower operational and maintenance costs, said the YAA.
With the call sign G-YAAC, it flew on the weekend and is to operate from the Nostell Estate, near Wakefield.
The other new helicopter - G-YOAA - is expected to be in service later in the year and will be based at RAF Topcliffe near Thirsk.
Its two current helicopters G-SASH and G-CEMS are to have a phased retirement once the new aircraft are in operation and will eventually be sold to help the replacement costs.
The work of the charity's helicopters has been featured on the BBC TV series Helicopter Heroes.
The cost of the new aircraft has been met through planned savings, grants and donations, said the charity.
A new £6m helicopter has entered service with the Yorkshire Air Ambulance (YAA).