Mizoram rode on a solitary goal by Beingaichho Beokhokhei to show five-time champions Kerala the exit in the 64th National Football Championship, for the Santosh Trophy, at the Yuba Bharati Krirangan in Kolkata on Wednesday.
East Bengal forward Beokhokhei scored the decisive goal in the 62nd minute.
Mizoram thus joined last year's runners-up Bengal, Tamil Nadu and Delhi in Group B of the quarter-final league that gets underway on Thursday.
Having beaten Assam 5-2 in their last match to make the last 16, Mizoram dominated right from the start and, barring occasional sparkle, Kerala could not make inroads.
The North-East outfit were impressive in the first 45 minutes but their strikers could not convert their chances inside the Kerala box.
Kerala had a couple of opportunities but K Rakesh and M P Sakeer drew blanks.
After the changeover, Beokhokhei had a solo run. The striker deceived the Kerala defenders and goalkeeper K Sarath to find the back of Kerala net and settle the issue.