Kangaroos are classified as nocturnal animals but not all kangaroos are active at night. There is always an exception to the rule. Kangaroos are known to be nocturnal, this means they are more active at night but quite a number of them are diurnal which means they can be active during the day and at night.
The red Kangaroos and the tree Kangaroos are known to be active at night. The nocturnal Kangaroos have a special auditory nerve which aids their vision at night. These sets of Kangaroos are best seen at dawn or dusk. The grey Kangaroos are mostly diurnal. They can be seen at any hour of the day.
The question is posed as 'all' kangaroos, and of course, there are probably a few who do not fit this description—but yes—generally speaking, kangaroos are most active at night. In fact, in Australia, visitors and locals alike are advised against driving at night, dusk, and dawn. Kangaroos are considered nocturnal but it wouldn't be impossible to see a herd of them hopping through the grasslands during the day.