Bell came to the crease with his team in deep trouble on 28-3, but his innings of 109 that spanned just over five hours, frustrated the Australians when they would have scented an England capitulation.
Jonny Bairstow hit 67 and contributed to a fifth-wicket partnership of 144 with Bell. But his late dismissal to a full toss from part-time leg-spinner Steve Smith, and the subsequent fall of Matt Prior, undermined England's rear-guard effort as Smith ended with 3-18.
Tim Bresnan, on 7, and night-watchman James Anderson, on 4, were the not out batsmen at close on a day the Australians had the best of, considering they lost the toss and had to bowl in hot, sunny conditions on a batsman-friendly pitch. Recalled fast bowler Ryan Harris claimed 3-43.
"I guess we would have taken where we ended up — at 28 for three," Bell said. "Although it was disappointing to lose those wickets at the end, we didn't have a bad day. Hopefully we can still get up to 350 as there is still quite a bit of batting to come."
Harris said Australia was also pleased with its day's work, though he admitted the team was frustrated by Peter Siddle's no-ball which bowled Bairstow on 21. The score would then have been 171 for five.
"It's not acceptable, it cost us a lot of runs today and potentially, it could cost the Ashes," said Harris, who was recalled for his first test in 15 months after an injury-plagued period. "But the unfortunate thing is that it was his only no-ball in the day. (Coach) Darren (Lehmann) wasn't happy. "
He added: "For me personally it felt great to be back playing for Australia, especially in an Ashes test at Lord's... Bell and Bairstow played well though we probably didn't help ourselves after lunch and bowled too many half-volleys."
Bell's latest century took him level with Leonard Hutton on England's list of test centurions, with 19, while he also became the eighth England batsman to go past 1,000 test runs at Lord's. But his 211-ball innings that included 16 boundaries meant much more than historical success.
Bell initially fought to deny a buoyant Australian attack before playing like his more fluent self. His 109 at Trent Bridge in the first Ashes test had been equally significant to the team's cause, setting up a tense 14-run win in the five-match series opener. Previously, he had scored 115 in Sydney in January 2011 at the start of his three-century run.
This latest effort was no less impressive as he played patiently but still punished anything wayward. England took 16 off James Pattinson's 14th over, with three boundaries coming off the bat of Bell. Pattinson went wicket-less for 79 runs in the day.
Australia captain Michael Clarke gambled with the introduction of Smith and his eventual success raised the question he maybe should have come on earlier than the 77th over when Bell and Bairstow were well established, especially as front-line spinner Ashton Agar was nursing a leg injury.
Bell, having registered his century with two runs through backward point, smashed a Smith full toss to the mid-on boundary to go to 109 but then edged a well-directed leg-break to Clarke at slip next ball.
Bairstow failed to carry on England's momentum as he was caught and bowled off a full toss, before a rash Prior stroke earned Smith his third victim four overs later, to a catch behind.
Jonathan Trott, with 58, earlier helped Bell with the recovery mission but a casual pull shot to deep backward square leg off Harris capped a wasteful end to what had been a good innings.
England's batting was shaken early in the day as they lost Alastair Cook (12), Joe Root (6) and Kevin Pietersen (2) within the first six overs.
Cook was trapped on the back foot to be lbw to Shane Watson, before bustling fast bowler Harris had Root lbw and Pietersen caught behind in his third over. Root referred his dismissal and though the replay did show a deflection the third umpire ruled that it was pad first.
Australia dropped left-arm fast bowler Mitchell Starc in favour of Harris, while No. 3 batsman Usman Khawaja came in for Ed Cowan. England omitted fast bowler Steven Finn and picked Bresnan.
The match began 15 minutes later than normal as both teams lined up to meet Queen Elizabeth II.