James Thompson and Josh Fowler scored first half tries and stand-off Jamie Lennard kicked both conversions, but Phoenix trailed 14-17 at half time.
Andy Ellis and Adam Kettle touched down in the second half and Lennard added another conversion put them 26-24 ahead with minutes remaining. Ilkley were awarded a late penalty but it sailed just wide.
Doncaster lad Sam Bottomley has joined Phoenix from Harrogate, while Ryan Peacey has retired.
Phoenix host Firwood Waterloo in their first ever National League game on Saturday.
Wheatley Hills start at home to Dinnington in North One East.
Prop Jack Latham (knee), Chris Blessed (ankle) and second row Dan Undy (knee) are all out injured after a problematic build-up to the season, which also saw Hills concede their Yorkshire Cup match at Pocklington last Saturday.
Centre Zak Mears has joined from Hemsworth and second row Rory Kynman has rejoined Wheatley from Morley. Club stalwart Andrew Penno has retired.
Promoted Thornensians face Wetherby in Yorkshire Two – the team they beat in the final of the Yorkshire Silver Trophy in May.
Thorne have signed fly-half Andy Barrass from Hull Ionians, as well as hookers Ben Robson from Leodiensians and Chris Hewitt from Scunthorpe, while they have a new Irish flanker in James Currie.
Yorkshire Two sideWath on Dearne beat Bradford Salem, of Yorkshire One, 24-17 to progress to the third round of the Yorkshire Shield.
Last season’s Yorkshire Five Plate winnersRossington Hornets begin their league campaign at home to Thirsk on Saturday.