Yes, "my bad" is a proper English phrase.
It is an apology; when you say "my bad", you're basically saying, "I admit a mistake" or "my fault, sorry for that".
Wiktionary says : (colloquial) (idiomatic)
My fault; mea culpa.
Yes, I realize the humvee isn't supposed to be parked in the heirloom flowerbed.
My bad.
It also links to this Language Log entry , which provides further insight: The authoritative discussion of the phrase "my bad!"
at this Random House site says it originates in pick-up basketball as a phrase used by young urban players when admitting to an error.
It has spread to other domains and is now used widely to mean something like "I admit that I have made a mistake.
" It was nominated for "word of the year" (not that it's a word, it's clearly a phrase) in 1999, but in fact it was already at least twenty years old by then.
english.stackexchange.com/users/300/RegDwigнt
It's proper English slang .
I wouldn't go so far as to say it was proper English.
It will certainly be effective in irking English teachers, haters of textspeak, and other grammar purists!
english.stackexchange.com/users/2181/thesunneversets
To my ear "my bad" is very much an Americanism.
Handle with care.
english.stackexchange.com/users/5130/Concrete Gannet
Concrete Gannet is right.
"
my bad" is very much an Americanism.
I had not heard this until recently, and was baffled when I did.
I heard it on American television programmes and a computer game.
I have not heard any British people use it.
To me, it's like the Americanism "I could care less".
It does not actually, make sense.
It might be acceptable and even considered as proper English in the USA
but, it is not elsewhere.
At least not in the UK.
It does not make sense because, it is an unfinished sentence.
When I have heard it, my immediate thought was, "your bad what?".
Your bad behaviour?
Your bad language?
Or, just your bad English, which this sentence demonstrates?
english.stackexchange.com/users/19290/Tristan
I think it is a short way to apologize: many people are ashamed when they realise they have been wrong about something, so this may be a shorter and faster way to admit that they were wrong and/or to apologize.
english.stackexchange.com/users/12898/Melisa
I have seen many people use the phrase "my bad" in Internet forums. What does it exactly imply and is it a proper English phrase?
Is "my bad" a correct English phrase?
english.stackexchange.com
<phrases><grammaticality><idioms><colloquialisms>
english.stackexchange.com/questions/5264
english.stackexchange.com/users/2189/Jay
Whilst this is considered English slang, there is disagreement as to whether this is considered proper English or not since it is an unfinished sentence. However, the phrase is used as a short way of apologising.  It is a correct English phrase to admit making a mistake. It is now widely used. It was nominated as phrase of the year in 1999. It is slang, and perhaps not proper English. It is an Americanism, so it needs to be used carefully. It doesn't make much sense, although considered acceptable in the USA.It is used as  a short form of apology
Whilst this is considered English slang, there is disagreement as to whether this is considered proper English or not since it is an unfinished sentence. However, the phrase is used as a short way of apologising.  "My bad" is a proper English phrase, but it is slang. It is an apology; when you say "my bad", you're basically saying, "I admit a mistake" or "my fault, sorry for that". It is said to originate in pick-up basketball as a phrase used by young urban players when admitting to an error.
"My bad" is an apology, meaning "I admit a mistake" or "my fault, sorry for that". Although used as a slang phrase, may believe that it is not proper English, as it is an unfinished sentence. There is disagreement as to whether this is considered proper English or not. However, the phrase is used as a short way of apologising or admitting a mistake.
It is a correct English phrase to admit making a mistake. It is now widely used. It was nominated as phrase of the year in 1999. It is slang, and perhaps not proper English.  It is an Americanism, so it needs to be used carefully. It doesn't make much sense, although considered acceptable in the USA. It is used as  a short form of apology
 "My bad" is a proper English phrase, but it is slang. It is an apology; when you say "my bad", you're basically saying, "I admit a mistake" or "my fault, sorry for that". It is said to originate in pick-up basketball as a phrase used by young urban players when admitting to an error.
For some people, this may be acceptable English or slang. For some people, this may not be proper English. This phrase is generally used as a way of apologising or admitting a mistake.