Sexton, who will return to Leinster from French side Racing Metro next summer, was flawless with the boot, kicking four penalties and two conversions, and outclassed opposite number Handrè Pollard.
Bowe went over himself to score Ireland's second try late in the game after getting on the end of Conor Murray's cross-kick.
And the 30-year-old lauded a stunning team performance, but admits Sexton is key for the Irish in the build up to the World Cup next year
"He is a fantastic player and such a good asset for Leinster to be getting back next year," he said.
"Going over to Paris he has showed his class and established himself over there, which is not always easy to do at a new club.
"It has definitely helped him, and when he puts on the green jersey he is another class above. He's a great asset for Ireland and a player I really enjoy playing alongside.
"It was a fantastic team performance today so we're all delighted, but I'm definitely not surprised we got the win.
"They are a top quality side and we knew it was going to be a very hard match but today we were right on the money.
"Our defence was excellent and we got off the line and put them under pressure, which really got the crowd behind us.
"I think after a performance like that of course you can see we're good enough to win the World Cup. We reckon we can beat anybody on our day, and it's just a case of doing it right and keeping that consistency
going over the next few weeks.
"We've got a great start today beating the Springboks, and knowing Joe (Schmidt) he'll be pushing us even harder next week so we'll be looking for three wins from three."
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