Djokovic, who has not lost in London since 2011, recovered from losing the first two games to win 12 of the next 13 in a 6-3, 6-0 win. He remains top of Group A with his final round-robin match against Tomas Berdych to come.
The Serb would guarantee the year-end number one ranking with another win on Friday, and it is hard to see who can stop him claiming a hattrick of ATP World Tour Finals titles on Sunday, The BBC reported.
Djokovic said that obviously Wawrinka wasn't feeling his best, adding that the Swiss made a lot of unforced errors, a low percentage of first serves in.
He added that on his side, he just played very solid from all over the court. He believes that he covered the court very well, got a lot of balls back, mixed up the pace, got Wawrinka off the comfort zone, which is something that was part of his game plan.
The Serb said that after he lost the first two games, obviously he didn't start so great. He added that he thought Wawrinka played very well the first two games. But he wasn't frustrated, and kept his calm.
Wawrinka went into Wednesday's evening session knowing victory would secure him a place in the last four, and he started the more confident player, firing two flowing forehand winners against the Serb.
He had ended a 14-match losing streak against Djokovic on his way to victory at the Australian Open in January, but Wawrinka was soon jolted back to reality.
A poor game including a double fault and a framed backhand gave Djokovic the break back to love, and from that moment the Swiss struggled to win points, let alone games.
Wawrinka admitted that it was not his best match, that's for sure, adding that it was also because Djokovic's playing really well, he's confident and not missing much.