McMullen has been named in a 15-man pool which was selected in consultation with former international Moneeb Iqbal, who acted as a Scottish South Asian representative in the meeting.
Richie Berrington will captain the side Down Under next month with wicketkeeper Matt Cross acting as his deputy.
Chris Greaves, who scored a match-winning 45 against Bangladesh on his debut in last year's tournament, is also included.
McMullen impressed in the recent Regional series and in A team matches with both bat and ball.
Head coach Shane Burger said on the Cricket Scotland website: "For us to have 40-plus names on the table for selection is testament to the system growing the talent base and providing the senior men's team with options.
"We have selected 15 that we believe will make the desired impact we are looking for."
Cricket Scotland, which was recently the subject of a damning report into institutional racism, released a detailed rundown of the selection process and criteria.
Former captain George Salmond chaired the selectors while Iqbal was an advisor and the players had an observer in Scottish Cricketers Association representative Ken Godsman. Cricket Scotland's interim head of performance, Toby Bailey, was also an observer.
Burger and assistant Craig Wright plus batting consultant Steven Gilmour were the only three listed with voting rights.
Scotland take on the West Indies in their opening match in Hobart on October 17.
Scotland T20 World Cup squad: R Berrington (capt), M Cross (vice-capt), G Munsey, M Leask, B Wheal, C Sole, C Greaves, S Sharif, J Davey, C MacLeod, H Tahir, M Watt, B McMullen, M Jones, C Wallace.
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