The former Royal School Dungannon star has a great track record as captain, having led the Ireland Under-20 side to an unprecedented Grand Slam and Six Nations championship double in 2007.
Pollock has also captained both the Ireland Under-19 and Under-21 sides at IRB World Championships in both grades in recent seasons.
Meanwhile, the Ulster front row for Thursday will welcome Bryan Young back to start at loosehead prop.
The Ballymena man has been injured since mid September and will play alongside BJ Botha and Neil Hanna against the Portuguese.
Hanna has been named at hooker and will be keen to get some game-time with his province - the Ballynahinch clubman has not featured in an Ulster squad since the pre-season friendlies in August.
The back-line is an exciting mix of youth and experience, with former Leicester Tigers out-half Ian Humphreys picked at number 10.
Former Ulster Academy star Mark McCrea and current Academy member Ian Whitten both start.
The try-scoring hero from the recent league win over Munster, Timoci Nagusa, also returns to the right wing with Bryn Cunningham named at full-back.
"This is a good chance for us to try and build on the Munster victory and also give some of our younger players a chance to show us what they can do."
Ulster Rugby season ticket holders should note that you can purchase discounted tickets up until 4pm on matchday (discounted tickets will not be available on the gate on match night).
Discounted tickets can be purchase via the Ravenhill ticket office (Monday to Friday, 9am-5pm), or via the Ravenhill Ticket Line (tel: 028 9049 3222, Option 2).
General release tickets for this friendly match can be bought by visiting the ticket section on the Ulster Rugby website.
ULSTER (v Portugal): Bryn Cunningham; Timoci Nagusa, Darren Cave, Ian Whitten, Mark McCrea; Ian Humphreys, Cillian Willis; Bryan Young, Neil Hanna, BJ Botha, Matt McCullough, Ed O'Donoghue, Thomas Anderson, David Pollock (capt), Robbie Diack.
Replacements: Nigel Brady, Justin Fitzpatrick, Declan Fitzpatrick, Kieron Dawson, Isaac Boss, Niall O'Connor, Paul Steinmetz, Chris Henry, James Sandford, Chris Cochrane.