Saturday's clash, which would book the Irish province's side in the European semi-final, is another landmark in an impressive year for the 34-year-old so far.
O'Connell started in the Lions' first Test against Australia last summer - before injury cut short his Tour - and achieved success with Ireland last month after a dramatic victory in France.
And he admits the outing against Toulouse will be another tie to savour - though he expects a fierce encounter.
"In Munster and Ireland we've got such an affinity with (Europe) and we're so used to watching Toulouse and their incredible style of rugby," he said.
"It's great to be at home but they are an incredible team with incredible players and incredible talent, it's a massive uphill task for us.
"They struggle at times, but I think they're in some ways a little bit like the French team, they have class across the park.
"And on the really big days, I think they're probably one of the best, if not the best, teams in the competition."