MySQL update table based on another tables value

I have a two tables,

Here is my first table,

ID      SUBST_ID        CREATED_ID
1       031938          TEST123
2       930111          COOL123
3       000391          THIS109
4       039301          BRO1011
5       123456          COOL938
...     ...             ...

This is my second table,

ID      SERIAL_ID       BRANCH_ID
1       039301          NULL
2       000391          NULL
3       123456          NULL
...     ...             ...

I need to some how update all rows within my second table using data from my first table.

It would need to do this all in one update query.

Both SUBST_ID and SERIAL_ID match, it needs to grab the created_id from the first table and insert it into the second table.

So the second table would become the following,

ID      SERIAL_ID       BRANCH_ID
1       039301          BRO1011
2       000391          THIS109
3       123456          COOL938
...     ...             ...

Thank you for your help and guidance.

UPDATE TABLE2
       JOIN TABLE1
       ON TABLE2.SERIAL_ID = TABLE1.SUBST_ID
SET    TABLE2.BRANCH_ID = TABLE1.CREATED_ID;

In addition to Tom's answer if you need to repeat the operation frequently and want to save time you can do:

UPDATE TABLE1
       JOIN TABLE2
       ON TABLE1.SUBST_ID = TABLE2.SERIAL_ID
SET    TABLE2.BRANCH_ID = TABLE1.CREATED_ID
WHERE TABLE2.BRANCH_ID IS NULL

UPDATE TABLE2
       JOIN TABLE1
       ON TABLE1.SUBST_ID = TABLE2.SERIAL_ID
SET    TABLE2.BRANCH_ID = TABLE1.CREATED_ID 
WHERE TABLE2.BRANCH_ID IS NULL or TABLE2.BRANCH_ID='';