Cockayne, 29, has been the stand-out winger during the early weeks of Super League XVIII, scoring six tries in the Wildcats' opening five fixtures.
"It is an honour to be selected," said Cockayne. "This is hopefully the first step to possibly playing for my country. To be recognised amongst the elite of English rugby league is my biggest honour to date and I can't wait to meet up with the rest of the England boys in the next couple of weeks."
His call-up completes a remarkable turnaround in fortunes for Cockayne, who was sacked by Hull KR two years ago following the latest in a series of breaches of club discipline. He was thrown a lifeline by his hometown club Featherstone and has not looked back since joining the Wildcats at the start of the 2012 season.
"We have been impressed with Ben's all-round form in Super League over a sustained period of time and he deserves his call-up," McNamara said. "We hope he can build on his selection and continue his progress as a top-class rugby league player."
Cockayne, who is likely to be fourth-choice winger behind Ryan Hall, Josh Charnley and Tom Briscoe, is the only surprise selection, with McNamara keeping faith with the majority of players that led England to victory in last season's autumn internationals.
Warrington forward Ben Harrison and ex-Leeds prop Luke Burgess are the only players from last year's squad to miss out, while Jon Wilkin, Eorl Crabtree and Ben Westwood return after being unavailable through injury. Danny McGuire and James Roby return after asking to be rested last year and Danny Tickle and Garreth Carvell are back in the fold.
The squad does not include Australia-based internationals like James Graham, Sam Burgess, Jack Reed and Gareth Widdop, all of whom are set to be named in McNamara's final squad which will be revealed after October's Grand Final.
The England-based players will meet up at RAF Cranwell in Lincolnshire over the weekend of March 16 and there will be another three get-togethers before the full squad head out to South Africa for a high-altitude training camp in early October. England will start their 2013 campaign with the International Origin match against the Exiles at Warrington on June 14.
C Ablett (Leeds), T Briscoe (Hull), R Burrow (Leeds), G Carvell (Warrington), J Charnley (Wigan), R Chase (Castleford), B Cockayne (Wakefield), E Crabtree (Huddersfield), L Cudjoe (Huddersfield), G Ellis (Hull), L Farrell (Wigan), R Hall (Leeds), Z Hardaker (Leeds), G Hock (Widnes), C Hill (Warrington), J Jones-Buchanan (Leeds), D McGuire (Leeds), M McIlorum (Wigan), A Morley (Warrington), L Mossop (Wigan), R Myler (Warrington), S O'Loughlin (Wigan), S Ratchford (Warrington), J Roby (St Helens), K Sinfield (Leeds), D Tickle (Hull), S Tomkins (Wigan), K Watkins (Leeds), B Westwood (Warrington), J Wilkin (St Helens).