The veteran openside has not played this season after he underwent shoulder surgery during the summer.
Williams' last competitive appearance was in the third and final Test for the Lions against South Africa on July 4 when he helped the tourists to a comprehensive 28-9 victory over the World Champions.
But the 34-year-old is now ready to pick up where he left off when the Blues host the Ospreys at the Cardiff City Stadium on Saturday evening.
Williams has been named in the No7 shirt by Blues coach Dai Young for the highly-anticipated Welsh derby clash.
And while his return is great news for the Blues themselves, Williams' recovery will also be a huge boost to Lions forwards coach and Wales boss Warren Gatland ahead of the forthcoming autumn internationals.
Wales take on New Zealand, Samoa, Argentina and Australia at the Millennium Stadium next month and Williams could now be in line for a starting spot against the All Blacks on November 7.