MacKenzie qualified for his second successive PDC World Championship in 2012 after defeating Royden Lam in the PDC Greater China Qualifier final. He beat Paul Barham 4-2 in the best of seven legs preliminary round match to make it through to the last 64 for the first time. He played former World quarter-finalist, Wayne Jones, and was beaten 1-3. In the rest of 2012 he lost in the quarter-finals of the Pacific Masters to Tony Carmichael and was also defeated in the semi-finals of the WDF Asia-Pacific Cup and Hong Kong Open. He entered the PDC Qualifying School in an attempt to win a 2-year tour card but could not finish in the top 4 on any of the four days, but finished high enough in the rankings to eventually play in the pro tour events during that year.