This squirrel is well adapted to the presence of people. It uses plantations (notably of coconut Cocos nucifera), and other cultivated areas providing some tree cover, secondary growth, town and rural gardens, bamboo forest, evergreen and semi-evergreen broad-leaved forest, even heavily degraded areas (Moore and Tate 1965, Lekagul and McNeely 1977, Suford 2010). It has been reported up to 2,500 m, but in some parts of its range it is usually found at lower elevations (Smith et al. 2008).
The Gray-bellied Squirrel is normally diurnal and arboreal (Saiful and Nordin 2004), although it sometimes descends to the ground to pick up food, which it then carries into a tree and eats. The diet consists of fruit and some insects. The spherical nest is built on the upper branches of a bush or small tree. The home range is small compared with other arboreal squirrels, and does not change in size seasonally.

It has been suggested that one of the reasons for low densities of this species in Malaysian tropical rain forest is competition from the great variety of other arboreal vertebrates (such as birds, and especially primates) for food, especially fruits and leaves, which are among the food items preferred by squirrels (Saiful and Nordin 2004).

This species is found widely in Thailand, Myanmar and West Malaysia, and small adjacent islands including Langkawi in the west (Moore and Tate 1965, Corbet and Hill 1992). It has been recently confirmed to occur in the small part of North Lao PDR west of the Mekong (Suford 2010, J. W. Duckworth pers comm. 2016). It has been claimed from Yunnan province, China (Wang 2003), apparently from only one locality, Xunjiansi of Mile in the southern part of the province. While this is plausible, the many instances of confusion with the similar-looking C. inornatus make it desirable that this identification may be corroborated. Although in some parts of its range it is predominantly a lowland species (Moore and Tate 1965), overall it has a wide altitudinal range.

There are no global conservation needs for this species, although some local needs haven't been suggested. For example, Saiful and Nordin (2004) stated the need for further comparative study on this species' abundance, density and distribution and its relationship to forest structure or habitat quality, spatially and temporally, in hill dipterocarp forest of Malaysia. However, for such a widespread and numerous species, the results would be primarily of academic, not applied conservation, interest.