Although, as you can see in the link below, there is some doubt as to whether this is true, the most common answer to this question is that the Hyksos introduced the chariot to Egypt as a new war technology. The Hyksos are also said to have introduced the compound bow to Egypt.
They Hyksos invaded Egypt sometime around 1700 BCE. Scholars still do not know for sure where they came from, but they believe that the Hyksos came from somewhere in Southwest Asia. The name “Hyksos” was what the Egyptians called them. It simply means “rulers of foreign lands.” They Hyksos used their superior technology to conquer Egypt. Eventually, the Egyptians were able to borrow enough of the Hyksos’ technology to be able to throw off Hyksos rule.
The most common answer to this question, then, is that the Hyksos introduced the chariot as a new war technology in Egypt.