Jason Steele became the first man since Stewart Downing in 2007/08 to play in every league game of the season this afternoon.
There was a debut for 21-year-old central defender Christian Burgess and places on the bench for England U-17 captain Bryn Morris and Ben Gibson, who ended a lengthy loan spell with Tranmere last week.
Tony Mowbray chose a 3-4-3 formation to start the game, with Burgess on the right, Andre Bikey centre and Rhys Williams left of a central densive three.
Justin Hoyte and Andy Halliday started wide right and left of midfield, with Richard Smallwood and Grant Leadbitter in the middle. Curtis Main headed the strike force, with Scott McDonald to the right and Muzzy Carayol to the left.
Former Boro striker Leroy Lita started, one of three changes from the Wednesday side beaten at Peterborough last Saturday. Out went Rhys McCabe, Giles Coke and Chris Maguire. In came Lita, David Prutton and leading scorer Jermaine Johnson.
The Wednesday fans gave a terrific rendition of "Hi ho Sheffield Wednesday" shortly before kick-off.
Their team responded with a determined start during which Burgess made two good, confidence-boosting, tackles.
Johnson sliced wide, then Seyi Olofinjana had a low cross cut out by Bikey with Lita waiting right behind in front of goal.
A burst of pace took Johnson in between two and into the Boro penalty area, where Burgess timed another tackle to perfection.
Keeping up the pressure Olofinjana volleyed just over from 14 yards.
A neat turn from Carayol midway inside the Wednesday half was let down by his second touch. Williams, with a well-weighted ball, sent Main away down the left in another move which ran out of steam.
Given the balance in the opening exchanges it came as no surprise when Wednesday took the lead with just over eight minutes played when David Prutton picked out Steven Howard deep in the Boro half.
He looked confident and single-minded as soon as he collected the ball and his first Championship goal for three years - and first in nine games since joining on loan from Hartlepool - duly arrived with a thundering strike into the roof of the net from not far inside the penalty area.
Boro responded, but couldn't create and as a result Chris Kirkland wasn't overworked.
Wednesday knew a win would be enough for them to stay up but weren't going to rely on a single goal advantage, and a low volley from Howard was deflected for a corner. Danny Pugh swung in a real teaser from the right which Steele could only tip over.
A scuttling run from Main ended with a powerful, low, cross-shot which flew through though the Wednesday six-yard box and out for a goal-kick.
Approaching the half-hour mark shots were traded as Johnson had Steele scampering to cover with a smart turn and low drive from 22 yards , then Main appeared to slightly mishit on from a similar distance from goal.
With 30 minutes and a few seconds played Wednesday added a second. Lewis Buxton swung over an excellent corner from the left which appear to go straight in. Leroy Lita, standing on the line, claimed the touch, but it brushed him at best.
They very nearly scored another just two minutes later. Burgess produced excellent tackle to deny Olofinjana, but was second to the loose ball and was barged out of the way. A cross was deflected, the ball fell to Howard and his low shot from eight yards was cleared off the line by Williams.
Half-time: Wednesday 2 Boro 0
Boro started the second half brightly and Leadbitter forced a save from Kirkland with 42 seconds played when he drove in a shot from 20 yards.
Swinging to the other end, Wednesday were gifted a chance when Burgess played a backpass to Steele from out wide. He hadn't seen Lita, who pounced and was left with a one on one, but Steele stood his ground and saved well.
With 55 minutes played Boro made their first change with Gibson replacing Smallwood. Gibson went into the back three, with Williams moving into midfield.
Dave Jones made his second change a minute later. Having replaced Johnson, who had been doubtful before the game with a hamstring injury, with Lee at half-time, he then withdrew Olofinjana, injured, replacing him with Jose Semedo.
Boro won their first corner of the game just short of the hour-mark and nearly scored from it as Burgess headed just over from Leadbitter's delivery.
A double Boro change followed with Halliday and Carayol replaced by Reach and Morris, who was making his league debut.
Two nice touches from the Hartlepool-born youngster kept Boro on the offensive and they were denied a penalty when Williams appeared to be fouled.
While Wednesday's fans knew a win here would be good enough they were still keeping an eye on scores elsewhere with Peterborough, Barnsley and Huddersfield occupying third bottom at various points of the afternoon. A goal for Derby would change all that - as for that matter would three for Boro!
A nasty clash of heads between Lita and Gibson flattened both players. Gibson was fit to continue, Lita was replaced but able to walk off. He was later found to have fractured his jaw.
At the final whistle the songs were of celebration for a Wednesday side who had battled through a difficult season but ensured this fixture would take place again next season.
For Boro, it was a season where early promise had failed to blossom.
At the end of the game hundreds of Wednesday fans invaded the pitch, making it difficult for Boro's players to salute their fans. But Leadbitter made it through, as did Bikey, who too the trouble to walk through empty terraces to give his shirt to a steward and point out a Boro fan.
Scorers: Howard, 8; Buxton, 30.
Sheffield Wednesday: Kirkland; Buxton, Gardner (Capt), Llera, Helan, Prutton, Pugh, Olofinjana (Semedo 55), Lita (Maguire 84), J Johnson (Lee 46), Howard. Subs: Bywater (gk); R Johnson, Taylor, Madine.
Middlesbrough: Steele; Burgess, Bikey, Williams (Capt), Hoyte, Leadbitter, Smallwood (Gibson 55), Halliday (Reach 66), McDonald, Main, Carayol (Morris 66). Subs: Leutwiler (gk); Haroun, L Williams, Ledesma. Order of subs on 66 1) Morris 2) Reach.
Referee: Andy Haines, Tyne and Wear.
Sheffield Wednesday: None
Middlesbrough: Bikey, 70, foul.
Attendance: 31,375 (1,444 Boro)
Conditions: Quite warm, dry, sunny and breezy.
Possession: Sheffield Wednesday 43% Middlesbrough 57%
Boro Website Man of the Match: A strong performance from Andre Bikey but Grant Leadbitter gets the vote.
Shots Cards Goals On target Off target Blocked Corners Yellow Red Wednesday 2 5 5 4 5 0 0 Boro 0 1 7 2 2 1 0