Allen posted his 20th shutout as a Blue in Monday's 4-0 victory, pulling even with former Blues goaltender Jaroslav Halak.
Allen and Halak trail only Brian Elliott (25) for the most shutouts all-time as a Blue.
"It's cool. To get into the 20s now, let's see if I can get to 30 at some point in my career," Allen said. "Hopefully a few more to come in the future. It's a credit to not just me, but to a lot of the boys in front of me doing a lot of hard work. I still remember my first shutout against Phoenix in 2012 or 13. It's come a long way."