Resuming on 60 with the team score reading 170/3, Smith showed no signs of relenting although he was troubled on a few occasions by Jofra Archer to continue his prolific run-scoring spree and bring up his third Ashes century in 160 balls by clipping Craig Overton off his pads for a couple of runs.
Post lunch, Smith continued in the same vein and shared a 145-run unbroken stand with skipper Tim Paine who brought up his sixth Test fifty and was batting on 58 from 128 balls. Smith got to his 150, his eighth such score in Tests and third against England by hitting Jofra Archer for three runs.
Paine was dropped on 49 by substitute Sam Curran and he was on that score for some time before reaching his fifty.
After scoring his hundred, Smith raised his bat as his teammates in the dressing room applauded in a fashion which showed the inevitability of yet another landmark from this run-machine, who returned to the team on the back of a concussion injury.
A light drizzle once again played spoilsport in the first session, but it was for a short while as the packed crowd at Old Trafford were treated to another Smith special.
Overnight batter Travis Head was the first wicket for England as Stuart Broad (3/47) trapped him in front.
Mathew Wade (16) played a poor shot to be caught at mid-on by England captain Joe Root. But Smith, at the other end, was batting at another level as he negotiated left-arm spinner Jack Leach's spinning deliveries well and showed superb technique against Broad and Overton to work his way through.
Brief scores: Australia 1st innings: 369/5 (Steve Smith 173 batting, Marnus Labuschagne 67; Stuart Broad 3/74)
( With inputs from IANS )