The Kelvin rises on the moor south east of the village of Banton, east of Kilsyth. At almost 22 miles (35 km) long, it initially flows south to Dullatur Bog where it falls into a man made trench and takes a ninety degree turn flowing west through Strathkelvin and along the northern boundary of the bog parallel with the Forth and Clyde Canal.
The river's first important (and considerably larger) confluence is with the Chantyclear Burn which originates from the ridge of Dullatur. It then continues its westward flow being joined by the often depleted (due to water being diverted to the canal) Shawend Burn to the west of Craigmarloch bridge. The next important tributary is the Garrel at a point south-east of Kilsyth south of Dumbreck Marsh. The Kelvin then passes through the large flood plain north of Twechar where it is fed by the Dock Water, Queenzie Burn, the Cast Burn and the Board Burn before reaching Kirkintilloch at its confluence with the more substantial waters of the Glazert and Luggie. It then flows past Torrance, meanders through Balmore Haughs, to the south of Bardowie where it joins the Allander Water, after which it takes a south-westerly direction towards Maryhill, Hillhead, through Kelvingrove Park before falling into the River Clyde at Yorkhill Basin in the city of Glasgow.
Wildlife along Strathkelvin include the grey squirrel, magpie, grey heron, cormorant, blue tit, great tit, chaffinch, snipe, great spotted woodpecker, blackbird, redwing, carrion crow, kingfisher, mallard, goosander, roe deer, red fox, otter, water vole, mink and brown rat.