Expatriates working in Saudi Arabia have to undergo a practical as well as a theory test for obtaining a driving license. Please click here to know the procedure for the same. It is quite common for expats to go on exit and return on a fresh visa. There are also cases where there is an internal transfer of sponsorship. In either case, as long as the license has still not expired, the expat need not give the driving test again just because his sponsor has changed. Here is the procedure for transferring the Saudi driving license details from your old to the new sponsor.
First, you must obtain a new iqama. Until you get your iqama, I would advise you not to drive even though you have a license. This is because, in case of any unfortunate incident involving your vehicle, you would be in deep trouble. There would be too many complications because you would be having a license with your old iqama, but now have no connection with your previous employer.
Once you obtain an iqama, first take an introduction letter from your new sponsor. This should be in Arabic and must specifically contain your new iqama number. Next, pay SR100 in either Riyad Bank or Al Rajhi Bank. You may do it either online or by using the machine in Riyad Bank for the same.
Now take a copy of your latest iqama. Attach all of these with your original license, two passport-size photographs and go to the traffic police station (Muroor) in your city. I would advise you to use the services of your Government Relations Officer for this. A form for transferring the license details is available in the police station. This has to be filled in (Arabic, of course) and submitted to the police along with all the documents mentioned here. After verification, the police will give a date and time when you can collect the new driving license. The details would have now got transferred in the system. You are now free to drive the vehicle until the expiry of the license.
A point to note here. In case your existing driving license is just about to expire, it would be worthwhile to give a fresh test and take a new license. This would save you time and money. Note that this license is valid for driving all over GCC, It goes without saying that having a valid Saudi driving license is definitely a plus point in your resume, while applying for a job anywhere in the Middle East :D