Would fillers give me a wider and more defined jaw? (Photos)

You will need a combination of different fillers not only to the jaw but also to the chin and a little cheek for more balance for get a wider jaw. I would inject Radiesse deep on the bone then layer Juvederm Voluma above to give that chiseled "squared off" look. The reasoning for different fillers is that they are made from different materials with a Radiesse as a synthetic calcium based product to stick to bone for width  and then Juvederm Voluma ( thickest ) layered on top to give that angular projection rather than the oval shape. Expect that it may take a minimum of 6 syringes to start. Make sure you seek out a well qualified injector because you want to change you face structure and dont want the filler to settle incorrectly.
Good Luck in your endeavors 

Hi Unneberg,
based on your photos, you are not that far off from achieving your desired jaw.  You would be a great candidate for chin and anterior jawline augmentation.  
The use of dermal fillers, layered over the course of several treatments, would help you to obtain your desired look. To meet your goals I would use a combination of Juvederm Voluma and Radiesse. Using these fillers in conjunction with one another would provide the perfect combination of width and definition.  
It is important to seek out a qualified injector to obtain a detailed consultation so that a personalized treatment plan can be tailored to your needs and the aesthetic you hope to achieve. 
Here is a video explaining more in depth using multiple fillers in one area. 
We hope this is helpful. Good luck and stay beautiful!
~ Mabrie Facial Institute