Source: https://community.spiceworks.com/how_to/145013-migrate-local-user-profile-to-domain-profile
This post is meant as an archive of this information due to its overall usefulness. Everything hereafter is credit to Felix Gorovodsky.
Step 1: Step 1
Join computer to new domain and restart it
Step 2: Step 2
Login in on old local account
Step 3: Step 3
Grant full permissions on your home folder, such as C:\USERS\testuser, keep in mind to check the option to replicate permissions to all child objects. Don’t worry about not setting permissions on few folders like Documents/My music/Pictures etc. These are not real folders, they are just links, so no permissions can be set. Just ignore them.
Step 4: Step 4
After this open Regedit
Step 5: Step 5
Right-click on HKEY_CURRENT_USER and select permissions
Step 6: Step 6
In new window click Advanced, then Add, and then type in DOMAIN ACCOUNT NAME. You may need to provide domain admin credentials to query AD.
Step 7: Step 7
Select user, then check following options:
A- Apply to: This Key and subkeys
B- Full Control
C- DO NOT SELECT LAST CHECKBOX – apply these permissions to objects and/or containerswithin this container only
Step 8: Step 8
Click Ok, then ok, then ok
Step 9: Step 9
Wait till finish and restart computer
Step 10: Step 10
Login to domain account, this will local profile, store SID information in registry etc.
Step 11: Step 11
Logout from domain profile, restart and login to local admin account
Step 12: Step 12
Open registry, navigate to HKLM\Software\Microsoft\Windows_NT\CurrentVersion\Profile List
Step 13: Step 13
Find the one, with local path to profile in key: ProfileImagePath, copy value of this key, eg. C:\Users\test.local
Step 14: Step 14
Find the other one with newly created profile path, eg. C:\Users\test.user.domain
Step 15: Step 15
Replace value of ProfileImagePath from old profile, eg. C:\Users\test.user.domain with C:\Users\test.local
Step 16: Step 16
Double check permissions for folders, check value of the keys.
Step 17: Step 17
If everything is ok, reboot computer and try to login to new domain profile. You should be welcomed with old desktop and settings.
Step 18: Step 18
One thing to remember, all outlook passwords need to be re-entered since credentials storage is wiped.