The powerful right-hander started out all guns blazing and, after being struck on the head by a Stuart Broad bouncer, he dug in to post his highest Test score and share a fourth-wicket partnership of 145 with Steve Smith.
England, seeking to win a home Ashes series 4-0 for the first time, endured a tough day in the field after handing shock debuts to all-rounder Chris Woakes and left-arm spinner Simon Kerrigan who conceded 53 runs in eight nervous overs.
Australia captain Michael Clarke won the toss and had no hesitation in choosing to bat under clear blue skies on a wicket which traditionally offers little help to bowlers.
England made a breakthrough with the total on 11 when James Anderson drew David Warner into a loose drive and the opener, on six, edged a regulation catch to wicketkeeper Matt Prior.
Anderson and Stuart Broad bowled tight opening spells but there was precious little movement and captain Alastair Cook soon turned to off-spinner Graeme Swann.
Chris Rogers played out three successive maidens from Swann but runs flowed more freely at the other end, Watson hitting three fours in an over off Woakes who struggled to find a good length.
Watson pulled Woakes powerfully for another boundary and danced down the pitch to lift Swann over long-on for six before reaching his half-century with a single from Kerrigan’s first ball in Test cricket.
Watson smashed the spinner for 28 runs off his first two overs and he had made 80 when Australia took lunch on a healthy 112 for one.
Broad bowled a hostile spell at the start of the afternoon session and Swann removed Rogers for a painstaking 23 off 100 balls, the left-hander edging a turning delivery low to Jonathan Trott at slip.
Watson, on 91, was struck on the side of the head by a ferocious short-pitched delivery from Broad and Clarke, after taking 39 balls to get to seven, was bowled by a fine delivery from Anderson which nipped back to bowl him off his pad.
It was Anderson’s 326th Test wicket, moving him above Bob Willis to second in England’s all-time list behind only Ian Botham on 383.
After 41 minutes in the nineties Watson drove Anderson through cover for three to reach his third Test hundred and he celebrated by removing his helmet and raising both arms high in the air.
He should, however, have become Anderson’s 327th victim when, on 104, he edged the ball to Cook at slip but the captain spilled a simple catch.
Woakes returned to the attack to bowl a much tidier second spell but Kerrigan’s suffering continued, an embarrassing waist-high full toss easily dispatched to the boundary by Smith before Australia moved on to 183 for three at tea.
Runs continued to flow in the final session as Watson passed his highest Test score and reached 150 by flicking Broad for four.
Smith got to his half century, off 113 balls, and Watson survived an lbw appeal off Woakes, correctly reviewing the decision after being given out.
England took the second new ball and finally made the breakthrough when Watson pulled a short ball from Broad to deep backward square leg where Kevin Pietersen held a superb diving catch.
Watson received a standing ovation as he trudged back to the pavilion after nearly six hours at the crease, his first Test century for three years including one six and 25 fours.
Smith will resume on 66 in the morning with nightwatchman Peter Siddle on 18 when Australia will look to press on past 500 to lay the platform for a morale-boosting win ahead of the next Ashes series staring in Brisbane in November.