PurposeThis study aims to distinguish how unabsorbed and absorbed slack affects market and financial performance via proactive and reactive supply chain resilience (SCRES), particularly under varying conditions of organizational ambidexterity.Design/methodology/approachBy collecting survey data from 277 Chinese manufacturers, we verify the conceptual model applying structural equation modeling.FindingsProactive SCRES mediates the positive impacts of both unabsorbed and absorbed slack on market and financial performance, whereas reactive SCRES mediates only their positive effects on financial performance. High levels of organizational ambidexterity strengthen the indirect effects of both types of slack on market and financial performance via proactive SCRES, but not when mediated by reactive SCRES.Originality/valueWe introduce a new theoretical perspective to view fits (as mediation) between the use of unabsorbed/absorbed slack in different ways when switching attentions to proactive or reactive SCRES, both of which can be improved through organizational ambidexterity. This study offers novel insights into how managers can switch attentions between proactive and reactive SCRES knowing when to appropriately use unabsorbed/absorbed slack for which purposes, and the use of different learning modes (explorative vs exploitative).