We consider Carlitz q -Bernoulli numbers and q -Stirling numbers of the first and the second kinds. From the properties of q -Stirling numbers, we derive many interesting formulas associated with Carlitz q -Bernoulli numbers. Finally, we will prove β n , q = ∑ m = 0 n ∑ k = m n 1 / ( 1 - q ) n + m - k ∑ d 0 + ⋯ + d k = n - k q ∑ i = 0 k i d i s 1, q ( k , m ) ( - 1 ) n - m ( ( m + 1 ) / [ m + 1 ] q ) , where β n , q are called Carlitz q -Bernoulli numbers.