Williams, 22, is one of three debutants along with Ebbw Vale's Luke Crocker and Ethan Davies of Cross Keys.
Luke Treharne will captain the side against England, Australia and Kenya in Pool D.
The Emirates Airline Dubai Rugby Sevens takes place on 4-5 December.
"It is exciting to have Jordan [Williams] involved from the Scarlets and he has all the attributes to excel on the World Series," said Wales head coach Gareth Williams.
"Luke [Crocker] and Ethan [Davies] have graduated through the intense summer programme and have trained well alongside the Core Group once given that opportunity.
"Ethan's form in the Principality Premiership for Cross Keys has been fantastic and deserves a return to international competition following his time previously with the Under-20s,"
Wales Sevens squad for Dubai and South Africa: Luke Treharne (Wales Sevens, capt), Sam Cross (Wales Sevens, vice-capt), Ben Roach (Wales Sevens), Lloyd Evans (Ospreys), Owen Jenkins (Blues), Luke Crocker (Ebbw Vale), Nicky Griffiths (Wales Sevens), Angus O'Brien (Dragons), Ethan Davies (Cross Keys), Kristian Phillips (Ospreys), Jordan Williams (Scarlets), Chris Knight (Wales Sevens).
Scarlets full-back Jordan Williams and Ospreys wing Kristian Phillips have been named in Wales' squad for the Sevens World Series in Dubai and Cape Town.