Astley, ranked 99th in the world, clinched a final-frame decider against the three-times UK finalist, who had fought back from 4-2 down to lead 5-4.
The 24-year-old Astley was delighted with what he sees as a landmark victory.
"It's the biggest win of my career so far. I was nervous when it came to the decider but I felt I controlled those nerves by taking one shot at a time to make sure I potted everything," he said.
"I've been playing really well in practice over the last month or so and obviously it's a case of doing it on the match table.
"I remember coming down here as a 12 or 13 year-old to watch the UK Championship so to think I've come and won my first match here today, it's quite a special moment."
Jimmy White also booked his place in the second round, but the 1992 UK champion was made to work hard by Michael Wasley in a 6-4 win.
White appeared to be in control at 3-1 up at the interval, but Wasley came back strong to level at 3-3. The Whirlwind then reaffirmed his domination by taking three of the next four frames to book a second-round date with Stuart Bingham, who demolished Ahmed Saif 6-0.
"It wasn't a great game of snooker as there were a lot of balls missed but I'm very pleased to win," White said. "I'm ok in the balls and am scoring well but because of my foot injury, my practising has just been routines and I haven't been playing any matches.
"At 3-1 up I was in control of the match but then it went 3-3 and he touched a ball with his shirt and called a foul which was very honourable of him, and I then went 5-3 up. He won a good game to go 5-4 because he'd missed a couple of balls in that frame.
"I'm pleased to have got through to the next round because obviously I'm struggling to stay on the tour so there's a lot of pressure on me.
"I've got a few days left before my next match. I'm going to stay in York and put a bit of practice in with my coach Patsy Fagan, and hopefully I'll be in a bit more control next time."
Nigel Bond claimed a 6-3 victory over Craig Steadman. The former World Championship runner-up racked up the second-highest break of the tournament so far with a 129 on the way to a comfortable 6-3 win over world number 83 Steadman.
Graeme Dott beat fellow Scot Fraser Patrick 6-2, making two century breaks of 102 and 104, while Ali Carter - a semi-finalist last year - ousted Thai youngster Ratchayothin Yotharuck 6-1.
Judd Trump progressed to the second round with a 6-2 win over Gareth Green, Barry Hawkins whitewashed Alexander Ursenbacher 6-0 and Dave Harold downed Chen Zhe 6-1.
Meanwhile, Zhang Anda won 6-3 against Cao Yupeng in an all-Chinese affair, but Tony Drago's involvement in York was ended by Liu Chuang, who beat the former world number 10 6-1.
First round results - Thursday sessions:
Ebdon 6-1 Norman
Lines 6-2 Baird
Allen 6-1 Jones
Williams 6-2 Taylor
Davison 6-4 Greene
Chuang 6-1 Drago
Trump 6-2 Green
Harold 6-1 Chen
McLeod 6-3 O'Donnell
Anda 6-3 Yupeng
White 6-4 Wasley
Hawkins 6-0 Ursenbacher
Bingham 6-0 Saif
Astley 6-5 Doherty
Bond 6-3 Stedman
Carrington 6-2 Woollaston
Robertson 6-3 Yan
Dott 6-2 Patrick
Holt 6-1 Page
Morris 6-4 Cope
Carter 6-1 Yotharuck
Poomjaeng 6-5 Un-Nooh