Yeah i think be careful if the type of job is customer facing then the interviewers might think "oh if he comes in with black eyes and marks on his face it doesnt look good for the company." Howerver construction, security, and fitness type jobs I would say this would be a good thing to say about your boxing experience
It helped me getting my first sunday job (months ago) because it shows im a dedicated hard working individual. Sadly, the job was washing up in a mank cafe and I quit last month.
I used to put it on CV when I was leaving school many years ago when I was boxing as an amateur. I think when you're young there isn't really that much you can put on other than qualifications if you have any and most people, well blokes anyway, know a bit about boxing and it's a possible ice breaker in an interview. I got asked what i thought of the state of the heavyweight division when I got my first job! It would depend on the job, but I think that if you put it in you've got a good chance to show that you have discipline and are pretty healthy at least.
Fight one, was told.. sorry with hindsight; patronized, that I could have a bit of potential. Fight two, found out if your opponent has the cheek to hit you back, it hurt, and your legs can do Michael Jackson type dance movements without your brain seemingly giving instructions... No, that is not going on the CV!