The Saracens skipper caught Wasps' Charlie Atkinson in the face with his left shoulder in the 61st minute, with the match poised at 15-15.
Elliot Daly crossed early against his former employers, but four Jimmy Gopperth penalties gave the visitors a half-time lead of 12-8..
A second home try from Sean Maitland followed by a penalty from Owen Farrell to tip the game back in Sarries favour before the fly-half saw red for a poorly executed tackle.
Wasps capitalised on their man advantage with Tom Willis powering over and Gopperth knocked over the conversion, and two further kicks, to confirm the result. And in his 100th game for Wasps, Jimmy Gopperth was flawless with the boot. The veteran New Zealander kicked 23 points, with Saracens players showing their frustration long before Farrell's indiscretion.
There was a feeling that Mark McCall's Sarries would eventually overpower their less experienced opponents and it seemed that way until fly-half Farrell was red-carded. After Farrell's dismissal Wasps were able to build pressure and the consistency of Gopperth's kicking meant they did not need to fear a late Sarries onslaught as they backed up their impressive win at Bath last time out to consolidate their position in the Premiership's top four.
Saracens director of rugby Mark McCall said "I watched it [Farrell's tackle] live but have not watched it on the video. He was chasing his own kick and was desperate to make a tackle and clearly got it wrong and he got his red card. "It is what it is. He could easily have been out of the Leinster game for another reason - injury or whatever. "We have got plenty of good backs at the club so we will just rearrange our backline a little bit and get on with it."
Wasps head coach Lee Blackett said"Charlie [Atkinson] is up and talking. You know Owen, he is physical but he didn't mean it. "We know Owen is not that type of player - he plays on the edge but genuinely never goes over that edge. He got that slightly wrong. "It was Jimmy's 100th appearance for us. We joined at the same time and he has been incredible for us over the last five years. "He'd led us really well. It doesn't really matter where you play him."
Saracens: Tries: Daly, Maitland Con: Farrell Penalties: Farrell, Goode.
Wasps: Try: Willis Conversion: Gopperth Penalties: Gopperth (7)
Saracens only defeat in the last six rounds of Gallagher Premiership Rugby was 12-16 to Bristol at Ashton Gate on 15 August. Sarries have won their last ten fixtures at Allianz Park in all tournaments since Northampton beat them there in round 1 of Premiership Rugby. Wasps have lost only once in the last seven rounds of Gallagher Premiership Rugby: 11-20 at home to Sale on 25 August.
Wasps have won their last three away games in Premiership Rugby, their best run on the road since February 2018. Wasps beat Saracens 60-10 at Ricoh Arena in round 11 but have not achieved a Premiership Rugby season’s double over them since 2006-07. Wasps only previous victory at Allianz Park was 64-23 in Gallagher Premiership Rugby in February 2016.
Saracens: 1. Richard Barrington, 2. Jamie George, 3. Vincent Koch, 4. Maro Itoje, 5. Tim Swinson, 6. Mike Rhodes, 7. Jackson Wray, 8. Billy Vunipola, 9. Aled Davies, 10. Owen Farrell, 11. Sean Maitland, 12. Brad Barritt, 13. Elliot Daly, 14. Alex Lewington, 15. Alex Goode. Replacements: 16. Kapeli Pifeleti, 17. Sam Crean, 18. Alec Clarey, 19. Callum Hunter-Hill, 20. Sean Reffell, 21. Tom Whiteley, 22. Dom Morris, 23. Elliot Obatoyimbo.
Wasps: 1. Ben Harris, 2. Tommy Taylor, 3. Biyi Alo, 4. Will Rowlands, 5. Tim Cardall, 6. Tom Willis, 7. Ben Morris, 8. Sione Vailanu, 9. Ben Vellacott, 10. Jimmy Gopperth, 11. Josh Bassett, 12. Mikele Bourgeois, Juan de Jongh, 14. Paolo Odogwu, 15. Rob Miller. Replacements: 16. TJ Harris, 17. Simon Mcintyre, 18. Jack Owlett, 19. Theo Vukasinovic, 20. Kieran Curran, Sam Wolstenholme, 22. Charlie Atkinson, 23. Will Simonds.