Under the new contract, 22 helicopters will operate from 10 locations around the UK.
Ten S-92s will be based, two per site, at Stornoway and Sumburgh, and at new bases at Newquay, Caernarfon and Humberside airports.
Ten AW189s will operate, two per site, from Lee-on-the-Solent and a new hangar at Prestwick airport, and new bases which will be established at St Athan, Inverness and Manston airports.
All bases will be operational 24 hours a day, and half of the new fleet will be built in Yeovil, Somerset.
The new deal will also see Bristow take over some of the civilian search and rescue (SAR) bases currently run by the Maritime and Coastguard Agency.