Dafür bin ich dir dankbar.

Dafür is a da- compound meaning for that, for it, or sometimes for this, depending on context.

In this sentence, it refers back to a thing, action, idea, or whole situation that was mentioned before.

For example:

• Du hast mir geholfen. Dafür bin ich dir dankbar.
  = You helped me. I’m grateful to you for that.

German often uses dafür instead of repeating the whole idea.

Because dankbar sein takes the dative for the person you are grateful to.

So the pattern is:

• jemandem dankbar sein = to be grateful to someone

That is why:

• dir = to you (informal singular dative)

Compare:

• ich → I
• mich → me (accusative)
• mir → to me (dative)
• du → you
• dich → you (accusative)
• dir → to you (dative)

So:

• Ich bin dir dankbar. = I am grateful to you.

A very useful pattern is:

• jemandem für etwas dankbar sein

which means:

• to be grateful to someone for something

In your sentence:

• jemandem → dir
• für etwas → dafür

So the sentence fits the pattern perfectly:

• Dafür bin ich dir dankbar.

You could also think of the more neutral underlying structure as:

• Ich bin dir dafür dankbar.

German often moves different parts of the sentence to the first position for emphasis or topic marking.

The more neutral order is:

• Ich bin dir dafür dankbar.

But if you put Dafür first:

• Dafür bin ich dir dankbar.

then the speaker is emphasizing what they are grateful for.

This is very common in German. The important rule is that the finite verb still stays in second position, so after Dafür, you get bin.

Yes. That is completely correct and natural.

Both are good:

• Ich bin dir dafür dankbar.
• Dafür bin ich dir dankbar.

The difference is mainly focus:

• Ich bin dir dafür dankbar.
  More neutral.

• Dafür bin ich dir dankbar.
  Puts more emphasis on for that.

So the version with Dafür first often sounds a bit more pointed or contrastive, as if the speaker wants to highlight exactly what they are grateful for.

Dankbar is an adjective meaning grateful.

In this sentence it comes after sein, so it is used as a predicate adjective. That means it does not take an adjective ending.

• Ich bin dankbar.
• Sie ist dankbar.

But before a noun, it would take an ending:

• ein dankbarer Mensch = a grateful person

So in Dafür bin ich dir dankbar, dankbar stays in its basic form.

In many cases, German prefers dafür when referring back to an idea, statement, event, or non-person thing.

So instead of saying:

• für das

German often says:

• dafür

This is especially natural when the reference is abstract:

• Du hast an mich gedacht. Dafür bin ich dir dankbar.

Für das is possible in some situations, especially when you mean a very specific noun phrase, but dafür is usually the more idiomatic choice when referring back to a whole previous action or situation.

Also note:

• da- compounds like dafür, darauf, damit are generally used for things/ideas
• for people, German uses the preposition + pronoun:
  • für ihn
  • für sie
  • für Sie

Normally, no.

Da- compounds like dafür usually refer to things, facts, actions, or situations, not people.

So:

• Ich bin dir dafür dankbar.
  = grateful for that/it (a thing or situation)

If you want to say for him/her/them, German uses:

• für ihn
• für sie
• für sie/Sie

So a native speaker would not normally use dafür to mean for him or for her.

You would use Ihnen.

So:

• Dafür bin ich Ihnen dankbar.

This means:

• I am grateful to you for that.
  with formal you

Compare:

• dir = informal singular you
• euch = informal plural you
• Ihnen = formal you

Examples:

• Dafür bin ich euch dankbar.
• Dafür bin ich Ihnen dankbar.

It is definitely natural, but it sounds a bit more thoughtful, serious, or heartfelt than a simple Danke.

Compare:

• Danke. = Thanks.
• Danke dafür. = Thanks for that.
• Dafür bin ich dir dankbar. = I’m grateful to you for that.

So your sentence is not strange at all, but it often sounds:

• a little more emotional
• a little more personal
• sometimes slightly more formal or reflective

It is especially suitable when you want to express real appreciation, not just quick politeness.

You can add adverbs very easily.

Stronger:

• Dafür bin ich dir sehr dankbar. = I’m very grateful to you for that.
• Dafür bin ich dir wirklich dankbar. = I’m really grateful to you for that.
• Dafür bin ich dir unglaublich dankbar. = I’m incredibly grateful to you for that.

A bit softer or more conversational:

• Ich bin dir dafür echt dankbar.
• Ich bin dir dafür wirklich dankbar.

So the basic sentence is already complete, but it is easy to adjust the tone.

In a subordinate clause, the conjugated verb moves to the end.

Main clause:

• Dafür bin ich dir dankbar.

Subordinate clause:

• ..., weil ich dir dafür dankbar bin.
  = ..., because I’m grateful to you for that.

This is useful because learners often know the main-clause form but want to see how it changes in longer sentences.

Yes: the whole pattern is worth learning as a chunk:

• jemandem für etwas dankbar sein

If you remember that pattern, you can make many sentences:

• Ich bin dir für deine Hilfe dankbar.
• Wir sind euch dafür dankbar.
• Sie ist ihm sehr dankbar.
• Dafür bin ich Ihnen dankbar.

That will help you much more than memorizing the sentence word by word.