Australia's Billy Stanlake (right) celebrates with Aaron Finch after taking the wicket of Sri Lanka's Dasun Shanaka during the Twenty20 match.
It was another massive wake-up call for the Sri Lankans, who arrived in Australia on the back of a 3-0 series win against Pakistan but have now been outplayed twice, after being crushed by 134 runs in Adelaide on Sunday.
They must now regroup for the third and final match in Melbourne on Friday.
Warner and Smith came together after Aaron Finch was caught down the leg side off Lasith Malinga for a golden duck, and the pair produced a batting masterclass. Warner was unbeaten on 60 and Smith not out 53.
Chasing 118 to win after Sri Lanka were restricted to 117 all out off 19 overs, they reached their target with 42 balls to spare.
"The bowlers did a terrific job, we bowled in the right areas and created chances and restricted them to 117, which wasn't enough on this wicket," said Smith.
"It's nice and easy batting at the other end from Davy," he added. "He's doing a terrific job. Played beautifully the other day and backed it up tonight as well."
Warner scored his first-ever T20 century when Australia crushed Sri Lanka on Sunday, and he brought that scintillating form into Brisbane.
In his first knock in the short format at international level since 2016, Smith was also firing - producing some glorious drives and clever singles as he and Warner raced each other to see who could make 50 first.
The explosive Warner won the battle, with his 14th T20 half-century coming off 30 balls, with seven fours. Smith soon followed, grabbing his third 50, off 32 balls, with six boundaries.
There was nothing the Sri Lankan bowlers could do against such quality batsmen, who were never troubled.
"It's a tough side and I think with this kind of batting line-up our score wasn't enough," said Sri Lanka skipper Malinga.
"We didn't get the score we expected and the batsmen will have to be more responsible. Shot selection is not that great and we didn't get any partnerships in the middle overs."
Two wickets from the towering Billy Stanlake, in for Mitchell Starc who was attending his brother's wedding, and a brace each for Ashton Agar, Adam Zampa and Pat Cummins kept Sri Lanka in check after they won the toss and batted.
Australia got an early breakthrough in the second over when Kusal Mendis was run out after a mix-up with Danushka Gunathilaka, who called for a run after hitting the ball then didn't move.
He attempted to make amends by opening his bat, clubbing a huge six off Stanlake, before his luck ran out and he was clean-bowled by the lanky paceman for 21.
Spinner Agar then enticed rising star Avishka Fernando into a big hit when on 17 and he skied it straight to Cummins, who took a difficult catch.
When Niroshan Dickwella fell to Cummins for five, Sri Lanka began to crumble.
Kusal Perera chopped onto his stumps on 27 and Dasun Shanaka went for just one, feathering a catch to wicketkeeper Alex Carey off Stanlake.
It left them in deep trouble at 75 for six after 11.2 overs and the wickets kept tumbling as Australia tightened the screws.
After Sri Lanka in Melbourne, Australia face Pakistan in three T20s in Sydney, Canberra and Perth.Scoreboard
Sri Lanka
D. Gunathilaka b Stanlake 21
K. Mendis run out (Agar) 1
A. Fernando c Cummins b Agar 17
K. Perera b Agar 27
N. Dickwella c Turner b Cummins 5
D. Shanaka c Carey b Stanlake 1
W. Hasaranga st Carey b Zampa 10
I. Udana c Richardson b Cummins 10
L. Sandakan run out (Cummins) 10
L. Malinga st Carey b Zampa 9
N. Pradeep not out 2
Extras (lb1, w3) 4
Total (all out, 19 overs) 117
Fall of wickets: 5-1 (Mendis), 2-29 (Gunathilaka), 3-53 (Fernando), 4-65 (Dickwella), 5-75 (Perera), 6-75 (Shanaka), 7-93 (Hasaranga), 8-98 (Udana). 9-109 (Malinga), 10-117 (Sandakan)
Bowling: Stanlake 4-0-23-2, Richardson 3-0-17-0, Cummins 4-0-29-2, Zampa 4-0-20-2, Agar 4-0-27-2
Australia
A. Finch c Perera b Malinga 0
D. Warner not out 60
S.Smith not out 53
Extras (lb2, w3) 5
Total (one wickets, 13 overs) 118
Fall of wickets: 1-1 (Finch)
Did not bat: G. Maxwell, A. Turner, A. Carey, A. Agar, P. Cummins, M. Starc, K. Richardson, A. Zampa
Bowling: Malinga 3-0-23-1, Pradeep 3-0-26-0, Sandakan 4-0-33-0, Hasaranga 1-0-18-0, Udana 2-0-16-0
Result: Australia won by nine wickets
Toss: Sri Lanka
Umpires: Gerard Abood (AUS) and Paul Wilson (AUS)
TV Umpire: Shawn Craig (AUS)
Match Referee: Javagal Srinath (IND)