Canada competed in the Davis Cup for the first time 109 years ago, defeating 28-time champions Australia in the final.
Earlier, Borna Coric had given Croatia the lead by upset Roberto Bautista Agut 6-4, 7-6(4) in the first singles match.
It was an emotional moment for Kokkinakis who won his first match for Australia since defeating Britain’s Dan Evans back in 2015.
By securing this invincible 3-0 lead in the playoff encounter, India was able to preserve its spot in Davis Cup World Group I.
The 12 winning nations from the qualifiers will directly join the World 1 team.
On the 4th and 5th of March, India will confront Denmark in a World Group playoff I encounter.
Nick Kyrgios was left out of Australia's Davis Cup roster after conquering the Australian Open last week.