At stumps, on the third day of the first Test, Pakistan were 409 for seven in reply to England's first innings 528 for nine declared, a deficit of 119.
Yousuf and Pakistan captain Inzamam-ul-Haq (69) shared a fifth-wicket stand of 173 in 42 overs which featured some of the best batting seen so far in this opening match of a four-Test series.
And he then added 99 with Kamran Akmal (58) before three overs from stumps the wicket-keeper became the first Test wicket for Kevin Pietersen, who dropped him on 26, when he was caught behind off the part-time spinner's fourth ball by opposing gloveman Geraint Jones.
Shahid Afridi was unbeaten on nought at stumps.
"They are a very good bowling side but I am in good form thanks to Allah," said Yousuf.
Since his conversion from Christianity to Islam became public late last year, just before England's tour of Pakistan, Yousuf's Test average has soared from nearly 48 to just over 92.
"When you pray five times a day you are very disciplined," Yousuf, formerly known as Yousuf Youhana and raised as a Roman Catholic, explained.
"I haven't changed my way of playing, or the way of my game, just the way of my life."
Yousuf, who scored a Test best 223 against England in Lahore in December, said he was proud to have got his name on the Lord's honours board.
"This is an historic ground and I am very happy to score a century here."
Meanwhile England seamer Liam Plunkett, who captured the prize wicket of Inzamam, admitted the hosts had endured a tough day.
"We had a great start on Friday. But we knew they had good batsmen to come and we let them get away from us today (Saturday).
"Inzamam and Yousuf are very experienced players. They scored a lot of runs against us in the winter and we need to think about what we can do to get them out."
Pakistan began the final session on 291 for five, Yousuf 132 not out and Abdul Razzaq 21 not out.
England then took the new ball and fast bowler Stephen Harmison had Razzaq (22) edging to Jones.
But Akmal's four through mid-wicket off Plunkett saw Pakistan past the follow-on mark of 329.
However, the keeper should have been out when he drilled the Durham quick low to cover where Pietersen dropped a catch he should have held.
Yousuf then went past 150 for the sixth time in Tests when he lofted spinner Monty Panesar for four having earlier struck him for six.
Akmal then steered Matthew Hoggard, who was playing with an injured hand, for a well-timed four through point.
Then a single off Paul Collingwood, whose Test-best 186 was at the heart of England's total, took Akmal to a 69-ball fifty with seven boundaries.
Pakistan's senior batsmen came together with their side precariously placed at 68 for four.
But come lunch the total had moved on to 165, Yousuf 66 not out and Inzamam, dropped early in his innings, unbeaten on 44.
Shortly afterwards, Inzamam completed an 89-ball fifty with seven fours.
Inzamam then played a superb stroke to whip Harmison through mid-wicket for four after the ball had pitched outside off-stump.
Not to be outdone, Yousuf brought up Pakistan's 200 by going down on one knee and stylishly driving Harmison's county colleague Plunkett to the cover boundary.
Collingwood, in the absence of injured Ashes-winning pacemen Simon Jones (knee) and Andrew Flintoff (ankle) was brought on by acting captain Andrew Strauss.
But Yousuf guided the medium-pacer's first ball to the third man boundary as he reached a 157 ball hundred with his 15th four.
It was the 31-year-old's 17th Test century and fourth against England.
However, a surprising misjudgment from Inzamam, jumping across his crease to turn Plunkett legside, saw him bowled after exposing his stumps to leave Pakistan 241 for five.
They resumed Saturday on 66 for three, Yousuf 20 not out, after Harmison had taken two quick wickets on Friday following hundreds by Collingwood, Alastair Cook (105) and Ian Bell (100 not out) against an injury-hit attack whose plight was made worse by several dropped catches.
Nightwatchman Mohammad Sami fell then for his overnight nought when he was caught behind off Hoggard.
Pakistan now had senior strokeplayers Yousuf and Inzamam in together on a good pitch. Plunkett almost dismissed Inzamam for 17. But leaping first slip Marcus Trescothick was unable to hold the difficult one-handed chance.