The midfielder struck with seconds of stoppage time remaining to cancel out substitute Shola Ameobi's 84th-minute penalty, which had looked like giving the Magpies their 19th home win of the season.
It was the second time Town had levelled with teenager Connor Wickham beating Steve Harper three minutes before the break after Andy Carroll had headed the champions in front.
But Ipswich and their former Sunderland boss Roy Keane could not prevent the Magpies from ending their home campaign unbeaten with 18 wins and five draws.
The game was played in front of a Championship record crowd of 52,181, the vast majority of them delighted home fans ready to acclaim their title-winning team.
It was the visitors who made the brighter start when Wickham's second-minute long throw found its way to skipper Walters.
The midfielder's first shot was blocked and keeper Steve Harper saved his follow-up with a foot.
At the other end, Carroll failed to make the most of keeper Brian Murphy's hesitancy when he ran on to Danny Guthrie's through-ball but could not find strike-partner Peter Lovenkrands five minutes later.
Newcastle were gradually working their way into the game, but Harper was relieved to see Jamie Peters' 18th-minute cross elude Walters, if only just, in front of goal.
The Magpies finally took the lead with 27 minutes gone when Wayne Routledge turned up on the left wing to beat full-back David Wright and fire in a cross which Carroll met with a thumping header to claim his 19th goal of the season.
But Ipswich were level three minutes before the break when Wickham got between central defenders Fabricio Coloccini and Mike Williamson and produced a fine right-foot finish.
Lovenkrands fired just wide seconds later and the home side responded, but Grant Leadbitter went equally close at the other end in a lively end to the half.
Town defender Gareth McAuley planted a free header wastefully over the bar from Leadbitter's 47th-minute corner, and Newcastle were far from having things their own way.
But they went close 12 minutes later when Jonas Gutierrez and Carroll combined to set up Lovenkrands, who could not hit the target as the angle was closed down.
Carroll headed wide from Jose Enrique's cross seconds later as the home side stepped up a gear, and Ameobi, club captain Nicky Butt on his final home appearance for the club and Joey Barton were all introduced in the quest for a winner.
The changes did the trick and when Butt was tripped by former Sunderland midfielder Grant Leadbitter, Ameobi calmly converted the penalty.
However, Walters levelled as the clock ticked into a fourth minute of added time to deny the home side victory.