PC Imran Mahmood, 36, inflicted the injuries on Jordan Walker-Brown in Harringay, north London, during the first coronavirus lockdown in May 2020.
Mr Walker-Brown, 23, broke his back when he fell backwards over a fence.
The officer said he had feared Mr Walker-Brown had a knife and believed he needed to be "contained".
PC Mahmood wept in the dock at Southwark Crown Court as the jury's verdict was delivered - after nearly 10 hours of deliberations - as did some others, although some people walked out of the courtroom shaking their heads.
Following the verdict, the Independent Office for Police Conduct (IOPC) said it was looking into whether PC Mahmood should face disciplinary action.
Speaking to reporters outside the court Mr Walker-Brown, who is paralysed from the waist down, said he had known what the verdict would be.
"I feel like he won before he got here, it's rigged, I was fighting against something that is bigger than everything.
"But I'm over it, it's done. Win or lose, it's a losing battle."
When he gave evidence last week, PC Mahmood described how he was one of a group of nine officers from the Met's territorial support group who were in a police vehicle when they saw Mr Walker-Brown walking down the road, on 4 May 2020.
The defendant told jurors he thought Mr Walker-Brown was wearing a small bag around his waist, and his suspicion was "heightened" because such bags were often used to conceal weapons or drugs and Mr Walker-Brown did not seem to be out for shopping or exercise.
The court heard that PC Mahmood and a colleague began following him on foot when Mr Walker-Brown started running away from them, climbing on top of a wheelie bin and scrambling on to an adjacent wall. It was at this point PC Mahmood Tasered Mr Walker-Brown, who fell and hit his head on a footpath.
The defendant told the jury Mr Walker-Brown had reached for his waistband while running and did not respond when asked to stop.
In a statement, the director of the IOPC Amanda Rowe said: "We note the jury's decision and acknowledge the devastating impact this incident has had on Mr Walker-Brown, who sustained life-changing injuries.
"We will now be considering evidence from the trial and liaising with the Metropolitan Police regarding disciplinary proceedings for potential breaches of police professional standards."
Det Ch Supt, Caroline Haines, who is responsible for policing in Enfield and Haringey, said after the verdict: "My thoughts today are with Mr Walker-Brown and his family whose lives have been changed forever.
"I don't underestimate the effect this incident will have had on them and have offered to meet with them when appropriate to listen to their concerns and discuss the matter in further detail."PC Mahmood has been on restricted duties since the incident.