One of the most famous phrases from The Wealth of Nations is that of "the invisible hand", a metaphor to explain how a market economy works. This is the partially unintended result of individual actions and it is not to be ascribed to anyone's rational design. By pursuing his own ends an individual promotes the improvement of society. Machiavelli too thinks of human actions as determined by tension between the randomness of circumstances (for which he use the term "fortuna", fortune) and the human skills to act in the face of this randomness and control it ("virtù", virtue).
In addition, both thinkers stressed the importance of a stable and fair government as indespensable conditions to favor economic growth and development. This link compares two passages on this topic from The Prince and The Wealth of Nations to illustrate the similarities between the two theorists:
In addition, you can also look at the passages in Smith's writings where he explcitly quotes Machiavelli: