Cats and owls have way better night vision than us. I don't think either could see in complete darkness but they can get pretty close. Both animals have a"tapetum" at the back of their eye.

This acts like a mirror to really make use of any light their eye can find. I couldn't find much information about the difference between cat and owl eyes as far as if one is better at night vision or not. Apparently owl's eyes are so big that they can't move them in their sockets like cats and humans can. That's why many of them have evolved the ability to rotate their heads at a range of 270 degrees.

Owls are definitely more sensitive to light than cats are. Cats are over 6 times as sensitive to light than humans. However owls are over 100 times more sensitive to light than humans. So, for example, if you were to look at a night sky you might see 6,000 stars but a cat can see over 40,000 stars and an owl can see over 1 million stars. Cats and owls are a lot more sensitive than us to low light so they can see stars that are fainter. So I guess, an owl probably has better night vision than a cat since it can see fainter light. I'm not entirely sure why this is so. It may have to do with differences in their tapetum (maybe owls have a larger tapetum?), the size of the owl eye compared to cat, or the amount of rod cells (or maybe the sensitivity of those rod cells) that the owl has. (Rod cells and cone cells both contribute to vision. Rod cells are involved in night vision and seeing black and white. Cone cells help us see color and are involved in how sharp are vision is or "visual acuity".)
Hope that helps!