The batsman came to the crease with Pakistan reeling at 7-2 early in the day on Wednesday, but proceeded to lead the revival with a patient 106 from 223 deliveries.
In reaching three figures, Younis became the first Pakistan player to make centuries against all nine Test-playing nations, and he also equalled the national record of 25 Test hundreds, set by Inzamam-ul-Haq.
Younis was eventually trapped lbw by Mitchell Johnson as Australia took the second new ball, and the 36-year-old was delighted with his achievement, after being dropped for the recent one-day international series.
"The feeling is very nice," he said. "It's an honour and I feel proud to become the first Pakistani to score hundreds against all countries.
"It was never in my mind before but when I scored a hundred in Sri Lanka it came on my mind, when I equalled [Mohammad] Yousuf's record of 24 then it came to my mind that I have no hundreds against Australia and then equalling the great Inzamam's record, it's an even bigger honour to be equal with him.
"It has never been easy for me throughout my career.
"Things keep going against me but all the time I play for my country and whenever my team needs me I go there and play positive cricket with positive body language and it was in my mind that if I do something here I will be a proud Pakistani.
"I think 400 plus would be very nice but it's not going to be easy and as a unit the Australians are very tough."