The 40-year-old Irishman, who is also a PE teacher at Cross and Passion college in Ballycastle, County Antrim, has previously been interviewed for the job, but lost out to Stubbs.
“It’s been a rollercoaster 72 hours to be honest. It’s all been very surreal,” Kearney said after signing a three-year contract. “I had an interview in the summer that went well and I got a really good feeling about the people in charge at the club.
“I didn’t get the job at that point, but I said, ‘What’s for you won’t go by you’, and here I am. There were a few things I had to sort out, but I feel at this stage it’s the right move for me and I can’t wait to get started.”
St Mirren chief executive Tony Fitzpatrick said: “We are absolutely delighted to have Oran in as our new manager. He is a highly impressive individual and I look forward to working with him.”
Kearney's first game will be a tough test at home to Celtic on September 14.