1. I do it always.

Is this sentence grammatically correct?

Can I end a sentence with always?

talab1234Can I end a sentence with always?

Yes, but that's usually for a special effect. We don't ordinarily end a sentence with 'always'.

Here are some special uses of 'always' at the end:

Pitching will be the team's main priority, as always.
Isn't it true that good things come in small packages, almost always?
Adjectives typically reflect the meaning of corresponding nouns, but not always.

talab1234I do it always.

Even though the grammar is not wrong here, this is not a good opportunity to put 'always' at the end. It's an ordinary sentence which we say as "I always do it".