The former Hibernian manager took charge on an interim basis after Brendan Rodgers sought an exit from the club midway through the season.
The Northern Irish manager made an impact straightaway after leading the Hoops to a string of victories. The most notable ones were the Old Firm derby wins and the Scottish Premiership title decider.
However, Lennon’s future at Celtic Park was under a cloud as the club pondered a lot whether to appoint him as the manager on a full-time basis.
Finally, Saturday’s 2-1 victory against Hearts handed him the permanent job – thanks to a brace from Odsonne Edouard.
The win also helped the Bhoys achieve a domestic treble for the third consecutive season.
Lennon said, (h/t BBC Football)
“It’s just a privilege.”
It came with massive pressure but I kept it boxed in. I’ve evolved. I’m older, I had four years away, it was always an ambition to come back and manage Celtic again so I’m pleased this day has come.
Lennon previously had a managerial spell with the Hoops, where his winning percentage steered up to 70, higher than Rodgers.
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The 47-year-old gaffer’s attention now turns towards the continental competitions, which has been a problem for the Hoops in their recent history.
The Celts will play Pinkafeld, Wiener Neustadt and FC St Gallen in the pre-season games.