The two-times world champion notched a 103 break and two half centuries as he raced into a 5-0 lead before Iranian opponent Hossein Vafaei finally got on the board.
Williams duly completed the job in the next frame, rounding off a 6-1 win and booking a final spot against world champion Mark Selby, who held off a spirited revival from Kyren Wilson in a 6-4 win in the second semi-final.
Williams stands just one win away from clinching an automatic place in the World Championship which begins on April 15 at the Crucible Theatre in Sheffield.
The 42-year-old knows his hopes of avoiding the dicey qualifying stage for the Crucible hinge on the result.
If Williams lifts the title, he will sneak into the all-important last 16 at the expense of fellow Welshman Ryan Day, who failed to qualify for this week's tournament, but if not he must play three best-of-19-frame preliminary matches to earn a place in the 32-man draw.
"I've been practising quite a bit lately. I know about the incentive that if I win the tournament, I qualify for the Crucible, but I haven't won in a while", said Williams.
"At the start of the week it was five or six games to qualify for the Crucible and looked out of my reach. Now it's only one match, it's within my grasp now really.
Read the full article on eurosport.co.uk: Williams to face Selby in China Open final with Crucible place on line