SummaryThis article introduces an extended looped‐functional for stability analysis of sampled‐data systems. It is defined as a differentiable functional over an interval between two consecutive sampling instants which has a property that the difference between its values at the latter sampling instant and at the former sampling instant is nonnegative. The proposed looped‐functional includes the existing discontinuous Lyapunov functional and looped‐functional as special cases. Based on the proposed looped‐functional, improved stability criteria are derived in terms of linear matrix inequalities. Three examples show the effectiveness of the proposed criteria in the view of maximum allowable sampling intervals.