Arthur Collins, 25, hurled the corrosive substance over a crowd on the dancefloor at Mangle E8 in what Judge Noel Lucas said was “a despicable act”.
Sixteen people suffered chemical burn injuries and three people were temporarily blinded - one of whom still suffers from blurred vision in one eye - of which 14 were the subject of charges.
Collins, the father of Ms McCann’s baby daughter Sunday, had told his trial he did not know the bottle contained acid, believing it to contain a liquid date rape drug, which he had snatched from two men after overhearing them planning to spike a girl’s drink.
But the jury at London’s Wood Green Crown Court convicted him of five counts of grievous bodily harm with intent and nine counts of actual bodily harm last month.
Judge Lucas ordered that as well as his 20-year prison term Collins, of Broxbourne, Hertfordshire, will additionally be subject to five further years on extended licence.
He branded Collins “an accomplished and calculated liar” who had shown “not a shred of remorse”, telling him: “This was a despicable act.
“You knew precisely what strong acid would do to human skin.
“Having thrown the acid over the club you slunk away and hid in the rear and pretended to be nothing to do with the mayhem you had caused.”
“In my judgement it was deliberate and calculated and you were intent on causing really serious harm to your victims.”
He continued: “He threw [the acid] on three occasions irrespective of the persons on whom it landed.
“His motivations for such a vicious course of conduct was nothing more than a perceived personal slight.”
Collins looked pale but did not react as his sentence was read out, and winked at his family as he was led to the cells.
There were cries of “love you Arthur” as he was taken away.
Twenty-two people reported injuries to the police after the acid attack at the club in Dalston, east London, on April 17, which was packed with bank holiday revellers.
Collins told his trial he had been out celebrating the news of Ms McCann’s pregnancy, which they had announced to her family the previous day.
CCTV showed him and co-defendant Andre Phoenix, 21, arriving at the club at about 9pm before getting into a confrontation with a group of men about four hours later.
At about 1am people could be seen clutching their faces and running off the dancefloor after Collins douses them with a liquid.
Clubbers dropped to their knees, shielded their faces with clothing, and rubbed ice on blistered skin.
Victims described a burning smell and their skin “blistering straight away” before everyone started “screaming, shouting, running”.
Collins and Phoenix were identified from the CCTV footage, in which Collins could be seen wearing a T-shirt with the word “candy killer” written on it.
Phoenix, of Tottenham, north London, was arrested on April 21 but Collins went on the run and was not apprehended until several days later hiding out in a house in Higham Ferrers, Northants.
Phoenix, a semi-professional cage fighter, was acquitted of four counts of grievous bodily harm and two of actual bodily harm after trial.
He had said if he had a problem with someone he would just “knock them out” and insisted: “I would never roll with acid.”
He was among Collins’ friends and family seated in the public gallery to watch him be sentenced.
At his sentencing hearing on Tuesday, the court heard Collins had threatened a similar attack on a former partner’s mother.
He received a caution for racially aggravated harassment for ringing the woman in the middle of the night and threatening her with an acid attack and to have her raped.
He has six previous convictions including threatening words, possession of cocaine, drunk driving and assault.
He was still subject to a suspended sentence for punching a man at a nightclub when he carried out the attack at Mangle.
Three of Collins’ victims - Phoebe Georgiou, 23, Lauren Trent and Sophie Hall, both 22 - told the court how the attack had changed their lives and left them living in fear.
But defence lawyer George Carter-Stephenson QC produced posts taken from victims’ social media accounts apparently showing their lives had returned to some kind of normality.
The judge was shown images of the girls in swimsuits on holiday and out in nightclubs.
Mr Carter-Stephenson said: “What I want you to do is simply appreciate that there has to be balance and to a certain extent they have returned to some normality following this.
“These victim personal statements give the impression that this has been all prevailing and has pervaded into every area of their lives and that’s simply not correct.”
The court heard that Collins had a lease on a Mercedes jeep despite being subject to a driving ban and owing £7,000 on his credit cards.
He said he had no assets to pay compensation to his victims, but Judge Lucas asked how he had been able to afford two hair transplants at a Harley Street clinic, remarking: “I suspect it wasn’t paid for by the NHS.”