Milan drew 0-0 at AS Roma on Saturday to clinch their first Serie A crown since 2004, meaning second-placed Inter's 3-1 win over Fiorentina on Sunday was academic as they waved goodbye to the title they have held for the last five seasons.
"Milan deserved it, they have a great side and the team that wins always deserves it," Leonardo told reporters.
The Brazilian was at the Milan helm last season in his first job as a coach and gave inexperienced Rossoneri full-backs Ignazio Abate and Luca Antonini, important players this term, their first chance to shine among other important groundwork.
He left at the end of the campaign after becoming frustrated by club owner Silvio Berlusconi suggesting tactics and then made a shock move to bitter rivals Inter in December following Rafa Benitez's departure.
Ironically, it was Leonardo's tactical naivety which cost Inter dear in the 3-0 derby defeat to Milan last month when his decision to shunt Samuel Eto'o onto the wing and play left back Cristian Chivu at centre half backfired.
"The crucial moment was the derby, if we had won it would have changed everything for us," the coach added.
His future at Inter seems secure judging by his comments and those of owner Massimo Moratti despite the end of their long stranglehold over a weak Serie A and media speculation linking the club again with Barcelona's Pep Guardiola.
The Brazilian cannot be blamed for the poor start to the season under Benitez when injuries and the Spaniard's failure to fill the large shoes of Jose Mourinho, who led Inter to a treble last term before heading to Real Madrid, weighed heavily.
They looked immediately more confident under Leonardo even if an overly gung-ho approach in the derby and the Champions League quarter-final defeat by Schalke 04 undermined much of his good motivational work.
An ageing Inter side must now be addressed, while reports saying Manchester United are keen on playmaker Wesley Sneijder have not gone away.
