The 24-year-old Edmund reached the semi-finals last year but will not get the chance to repeat the feat after a 6-3 6-0 7-5 defeat to Tomas Berdych which is set to drop him out of the world's top 20.
Edmund, the 13th seed, showed evidence that he is still suffering from a knee problem and was never really in the match against the experienced Czech, who has a strong record in the tournament.
Edmund called the result a "reality check" and admitted: "It just shows where I am at the moment, my level and stuff, and how much and where I have to improve.
"I've still got lots of years to play so obviously I'm confident I'll be playing at a good standard again, but you're always itching and competitive to get things done immediately.
"You just have to have patience and give stuff time to get better, including my game. I've lost matches when I'm fully fit, so I have to work on lots of things to get back up there."
Evans set up a second-round meeting with Roger Federer after winning his first main draw match at a grand slam in two years with a 7-5 6-1 7-6 (8) win over Tatsuma Ito of Japan.
The 28-year-old qualifier, who is still in the process of working his way back towards his former heights after a one-year drugs ban, is relishing the clash with Federer, who he also met in the third round of Wimbledon in 2016.
Evans said: "It's not very often you get to play Roger on a pretty big court, so I look forward to it.
"I feel pretty good. I'm getting there slowly by the day. I think I'm more mature, but I've obviously got to try and be smarter on the court – like when I get a chance, to take it straight away."
Cameron Norrie failed to build on reaching his first ATP Tour final last week as he was beaten in straight sets by Taylor Fritz.
Norrie went to Melbourne full of confidence after his run in Auckland, but lost 6-4 7-6 (6) 6-2 to the world number 50, who he had beaten in New Zealand.
Norrie missed his chance to draw level in a tight second set before falling away in the third as Fritz ultimately cruised into the second round.
Boulter claimed one of the best victories of her career with a 6-0 4-6 7-6 (6) success over experienced Russian Ekaterina Makarova.
it could have been embarrassing for the 22-year-old, who celebrated exuberantly after going 7-4 up in the tie-break – having forgotten the new rule which states final set tie-breaks are the first to 10.
The 22-year-old walked to the net only to realise her mistake but reacted impressively to wrap up victory after two hours and 24 minutes in oppressive Melbourne heat.
Harriet Dart was left in tears after a 6-0 6-0 defeat to Maria Sharapova, while compatriot Heather Watson was the first player to exit the tournament after a 6-1 6-2 loss to 31st seed Petra Martic.
The 26-year-old has found herself stuck in the tennis doldrums and admitted she was so tense on court that she felt faint and dizzy and had to call the doctor.
Watson said: "I haven't been like myself on court lately. I've got to change
something. I'm not going to continue like this."