Yes.. it is outside in the Arrivals side of the terminal. All good advice here....wish I'd found that post before we flew to CMB!!
...we used it yesterday/today and it is now 200 lkr per item per day (or part thereof)..in our case the security guy, once summoned, simply questioned us as to the contents of the bags.... and as we always have locks that aspect wasn't a problem. I can see it being a nasty surprise for some of course...
A very useful facility.....^ We were then able to hop the train to Galle on a HLO basis!