Watson described his team-mate as a chilled out character but also warned of the “hostile environment” he expects to encounter inside the Aviva Stadium.
Kinghorn has been picked to start at stand-off for the first time in a Six Nations game, with Finn Russell relegated to the bench.
It’s a bold call by head coach Gregor Townsend, given added intrigue by news emerging on Friday that Russell was among six players disciplined for visiting a bar in Edinburgh on their return from Rome last weekend.
The decision to select Kinghorn at ten follows the player’s impressive form for Edinburgh this season in the playmaker’s role following his conversion from a back-three player.
Watson has had first-hand experience of Kinghorn’s effectiveness at stand-off and believes he can transfer his club form to the international game. He also likened his club-mate to Russell in temperament.
“I think it’s really exciting,” Watson said of the selection. “I’ve been playing with Blair since he joined Edinburgh when he was 18 or something. I’m really happy for him; it’s exciting for him.
“I guess he’s similar in a way to Finn – he’s a very chilled-out guy off the field, very calm. I think that will help us on Saturday: I don’t think he’ll let the occasion get to him.
“He’s been great for Edinburgh this season, really exciting, and hopefully he can put that on the international stage.
“Finn and Blair are both chilled out characters. I don't think they let stuff get to them, and so I think you can expect similar things from them. But they're also both different people as well, although they have similar traits off the field.”
While Townsend’s decision to pick Kinghorn at ten caught many off guard, Watson thinks it’s a gambit that could pay dividends as Scotland seek a third-place finish.
“I'm not surprised,” said the flanker. “We all know what Blair can do. He's a great player. He's an exciting player and one the fans are going to really enjoy watching. Everyone at Edinburgh knows what he can do.
“It's a great opportunity for him and hopefully he can put his form with Edinburgh onto the field on Saturday.”
Scotland find themselves in a similar situation to last season where they can influence the destination of the Six Nations Championship on the final day without having a chance of winning it themselves. The win in Paris last March denied France the chance of winning this title. This time around, Ireland know that a win over Scotland would put them above the French ahead of Les Bleus’ game against England which doesn’t kick-off until 8pm.
“They have to concentrate on their game and not go out there chasing the game,” Watson said of Ireland’s likely strategy.
“We were in a very similar situation last year against France, weren't we? They had to go out there and get a big score and thump us and we saw what happened there.
“It will be a tough game for both of us because we have to play our own games. I don't think that is something to go out chasing straight away.
“It’s a very tough place to go and play. Quite a hostile environment. But we believe in ourselves and believe in the squad.”