After Shane Watson was the star of the opening day making 176 before falling just before stumps, it was the 24-year-old Smith who took on the starring role on Day 2.
Smith began the day not out on 66 with Australia commencing at 4-307 and after rain delayed the start of play, once it was underway Smith looked at ease at the crease once again.
He brought up his maiden Test century in style with a six shortly before the tea interval and then continued on afterwards with Australia chasing quick runs he moved on to 138 remaining not out from 241 deliveries from 16 boundaries and two sixes.
While Smith had shown signs of his batting abilities previously this series with two half-centuries and five 50s over his 11 match career to date, but it could be this 138 that is the making of him to cement him as a long-term Australian middle-order batsman.
Australian captain Michael Clarke declared with Australia 9-492 and then England faced 17 and-a-half overs before stumps finishing the day on 0-32 with captain Alastair Cook on 17 and Joe Root 13.
The London rain meant that play on Thursday didn’t begin until after lunch with Smith coming to the crease on 66 along with nightwatchman Peter Siddle who was 18.
Siddle copped a pearler of a delivery from James Anderson early on with the second new ball that cleaned up his off stump and he was gone for 23 before Brad Haddin joined Smith at the wicket.
The pair put on a partnership of 65 with Haddin there as Smith celebrated his milestone.
Smith brought up his maiden Test ton in style smashing a beautiful on-drive for six off the pedestrian medium-pace of Jonathan Trott just before tea on the second day's play.
While Smith is playing the 12th Test of his career, at just over 24 years of age he is the youngest Australian to score an Ashes century since Ricky Ponting did it aged 22 back at Leeds in 1997.
While Smith took advantage of Trott to smash his six to bring up his ton, Haddin took it too easy against the part-time and was bowled by Trott for 30.
That brought debutant James Franklin to the wicket for Australia with the score 6-385 and he added a quick-fire 23 from just 21 balls before giving Chris Woakes the first wicket of his Test career on debut.
Australia was simply out for quick runs, though, before declaring and Mitchell Starc added 13 from just eight balls and then Ryan Harris 33 from 27 with two sixes before skying a ball to be caught and bowled by Anderson leaving Smith not out on a brilliant 138.
Nathan Lyon then came to the wicket to replace Harris and Smith hit a cover drive off Anderson for a single the next delivery, but then Clarke played some mind games with the English before Anderson got to bowl a ball at Lyon.
That meant that Anderson didn’t get a chance to claim his fifth wicket and no doubt would have frustrated him.
Anderson was the pick of the English bowlers finishing with 4-95 from 29.5 overs with Graeme Swann taking 2-95 from 33, Stuart Broad 1-128 from 31 and Woakes 1-96 from 24.
Debutant left-arm orthodox spinner Simon Kerrigan didn’t bowl a single ball on Day 2 after the horror start to his Test career that saw him go for 0-53 from just eight overs.
However, the Australian batsmen had done the job by making a tremendous score of 9-492 and giving the England openers a tricky period to face before stumps.
Cook and Root got through relatively untroubled, though, to be 0-32 at stumps when bad light stopped play even though only three deliveries were left to be bowled.