Maqsood was ruled out of the showpiece tournament after suffering a lower back injury in a domestic match earlier this year, the Pakistan Cricket Board said in a statement.
"Sohaib is devastated to miss out on the World Cup as he had worked hard for this event and was in sparkling form," chief selector Muhammad Wasim said.
"We feel for him but injuries are part and parcel of the sport."
"...we have decided to include Shoaib Malik in the side. I am sure Shoaib’s experience will be handy for the entire squad."
Malik, 39, captained Pakistan in the inaugural event in 2007 and was a member of the side that won the title in 2009.
The all-rounder missed the 2010 World Cup in the West Indies but featured in the last three editions.
This was the fourth change to Pakistan's original squad, coming a day after they drafted in former captain Sarfaraz Ahmed, Haider Ali and Fakhar Zaman.
Pakistan will play warm-up matches against West Indies and South Africa before beginning their campaign with a blockbuster clash with arch-rivals India on Oct 24 in Dubai.