Malinga finished with 4-57 as Pakistan, already enjoying an unbeatable 3-1 lead in the series, slumped from 128-3 to 194-8 after they won the toss and batted on a flat Sheikh Zayed Stadium pitch.
Pakistan captain Misbah-ul Haq top-scored with 51 while in-form batsman Mohammad Hafeez, who scored three centuries in the series, made 41.
Anwar Ali chipped in with a fiery 38-ball 41 not out spiced with one six and two fours.
Pakistan, who had not been all out in the previous four matches of the series, found the going tough after openers Ahmed Shehzad (17) and Sharjeel Khan (18) by 13th over.
Also Read
Malinga then came into his own, sending Misbah back off caught behind and then trapped Abdul Rehman (one) to leave Pakistan struggling at 176-7. In between Ajantha Mendis had Umar Akmal (20) caught at short mid-wicket.
Misbah hit two boundaries and a six during his 74-ball knock, finishing with 1371 runs in 34 one-day matches this year -- the most by any player.
Sri Lankan brought in Mendis for paceman Nuwan Kulasekara.