Gul will be the fast bowling coach while Ajmal will handle the spin bowlers.
Both will accompany the team to Australia for three Tests which will be followed by five Twenty20s in New Zealand.
Gul was coach during Pakistan's white-ball series against Afghanistan in the United Arab Emirates and against New Zealand at home earlier this year.
He also coached Quetta Gladiators in the Pakistan Super League last season and was coach of the Afghanistan team during the last T20 World Cup in 2022.
Gul represented Pakistan in 47 Tests, 130 ODIs and 60 T20s between 2003-16.
Ajmal has 447 international wickets in all formats. A former No.1 ODI bowler, Ajmal played 35 Tests, 113 ODIs and 64 T20s for Pakistan and was famous for his 'doosra' - an off-spinner's delivery that turns away from righthanded batter.
"I am delighted to contribute to the development of spin bowling talent within the Pakistan national team," Ajmal said. "I believe my career and coaching experience will help enhance the spin bowling arsenal of the team."
Gul and Ajmal are among several new appointments made by the PCB since Pakistan made an early exit from the Cricket World Cup in India by finishing fifth in the 10-team tournament.
Captain Babar Azam resigned from the captaincy in all formats and Shan Masood was made Test captain.
Shaheen Afridi was appointed as skipper of the T20 side while former captain Mohammad Hafeez was named as team director, who will also be the head coach of the team on the twin tours of Australia and New Zealand.
Pakistan will play Australia in the first Test starting at Perth on December 14. Melbourne will host the Boxing Day Test starting December 26 with Sydney hosting the last Test match from January 3.
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