Hull City's loss to Tottenham at White Hart Lane sees the club confirm their Premier League status for another season, while the Black Cats also look unlikely to be caught
With Hull City beaten at Tottenham, a point was enough to put Leicester beyond the reach of Steve Bruce's men, who occupy the final relegation spot with one game left to play.
The achievement rewards a remarkable run of form for Nigel Pearson's battlers, who had won six out of seven fixtures prior to their visit to the Stadium of Light.
Leicester sat bottom of the table, without a win in eight and seven points adrift of safety when they lost to Tottenham on March 21.
Meanwhile, Sunderland - who have a game in hand over their relegation rivals - head into the final week of the campaign three points clear of Hull and one ahead of local rivals Newcastle United, who lost on Saturday at already relegated QPR.
Dick Advocaat's men, who went closest to finding a winner through chances from Sebastian Larsson and Danny Graham, round off their season with daunting trips to Arsenal and champions Chelsea.
Advocaat brought John O'Shea and Liam Bridcutt in for injured duo Wes Brown and Jordi Gomez, while Leicester recalled fit-again Andy King in place of Matty James, who has been ruled out for up to nine months with a knee problem.
It was the home side who started best and Larsson drew a diving save from Kasper Schmeichel with a curling 25-yard free-kick after six minutes.
Leicester might have snatched the lead with their first attack had Leonardo Ulloa managed to get his head on the end of a cross from the left, but the visitors were on the back foot again when Graham saw an effort deflected wide at the other end.
Graham, who netted his first Sunderland goal at Everton last weekend, then volleyed straight at Schmeichel after being played in by a wonderfully weighted chip into the box from Lee Cattermole, and the former Swansea City man was central to the hosts' attacking threat.
The 29-year-old's next contribution was to nod the ball down for Connor Wickham, who was unable to keep his powerful strike down as he blasted high and wide shortly after the half-hour mark.
Cattermole was left breathing a sigh of relief when he avoided a second yellow card for bringing down the advancing Riyad Mahrez a few moments after being shown his first booking.
Chances were few and far between throughout second half, but Patrick van Aanholt went close with a fierce strike across goal from 20 yards out.
Sunderland substitute Adam Johnson created an angle for himself in the 71st minute but his low drive was kept out by Schmeichel, whose attacking colleagues were struggling to test Costel Pantilimon in the home goal.
But despite failing to register a single shot on target, it was Leicester who eventually reaped the biggest reward at the final whistle with manager Pearson now able to plan for a second season in the Premier League.