The 26-year-old midfielder was sentenced to 130 hours of unpaid work and placed under a one-year supervision order when he appeared at Airdrie Sheriff Court on Wednesday.
But Sheriff Frank Pieri warned the former Celtic youth that the punishment was a "direct alternative" to custody and told him to behave in future or face prison.
Now his club boss has admitted McGowan avoided prison by the skin of his teeth.
Lennon said: "There is no doubt about it, Paul was a very fortunate chap.
"It's a hard punishment he has been given though and, by God, he will work hard on that - we will make sure he sticks with it.
"He's a St Mirren football player and with this all now behind him, we're looking to get the best out of him every week."
McGowan admitted kicking police constable Edward Gilmartin on the body and repeatedly kicking sergeant Tony Fitzpatrick on the body during the incident in his home town of Airdrie and then later at Coatbridge police office in the early hours of August 11 last year.
McGowan lashed out as he was being handcuffed by the officers but the player's lawyer Mark Lutton told the court his client's reaction was sparked when his restraints aggravated an old shoulder injury.
However, depute fiscal Stephen McLean informed Sheriff Pieri that McGowan's manner was so aggressive that his feet had to be bound before he could be transported to the police station.
But he was still so drunk by the time he got there that the police were unable to caution and charge him.
However, now that he has avoided a jail term, Lennon has vowed to stand by his player.
McGowan is in the Saints squad for the visit to St Johnstone on Saturday and the Buddies boss is eager to see the midfielder get back to his best.
"It's a big weight off his shoulders," said Lennon. "Anything like that hanging over you, regardless what you do, is going to have a bearing on you.
"I'm delighted [with the outcome]. He's a loveable wee guy is Paul and I'm delighted this is all behind him.
"We will help him in his recovery and he knows he has done wrong. The most important thing is that we help him along with his correction and that Paul gives a little back to the community for the right reasons. He needs to become a role model that youngsters will look up to.
"We have all made mistakes in our lives but we are one big family here at this club and like any family, if someone is in trouble, you stick by them."
Meanwhile, Conor Newton - who has been handed an extension to his loan deal from Newcastle until the end of the season - admits he is eager to emulate his United friend Paul Dummett.
Both players were sent north by Alan Pardew last term to gain first-team experience.
While Newton is still learning his trade in Paisley, Dummett has returned to St James' Park to establish himself as a first-team member.
Newton - out of contract in the summer - will spend next week training with his parent club as the coaches there seek to evaluate his progress and he hopes to show enough to merit a new deal come the summer.
He said: "The decision to stay here for the rest of the season made itself. I've been here for a year and really enjoyed it, so it was a no-brainer.
"Paul has drawn up the blueprint for how it is done. If I could take a leaf out of his book, I think everyone would be happy.
"But it's a tough one. He's gone down there, made his debut in the derby, scored against Liverpool and landed a new six-year deal. You can't expect to do exactly the same but I'll try my best."