Global climate change is increasing the frequency and severity of marine heatwaves, flooding, and storm events, posing a risk to habitat-formers that support marine biodiversity. Wamer and less saline waters are expected to impact the physiological performance of marine habitat-formers, such as seaweeds, but our understanding of the interactive effects of these factors is currently limited. In particular, the early-life history stages, which are a key bottleneck for many marine species, are often more vulnerable to stressors compared with the adult stage, hence investigating how environmental change may affect early life responses is fundamental for understanding how they will fare under future climactic conditions. We experimentally manipulated salinity and temperature during early life stages in one of the dominant habitat-forming macroalgae on Australia’s temperate coastline – Phyllospora comosa. To quantify the response of crayweed to the interactive effects of warming and lower salinities, we measured physiological responses of gross primary production, respiration, and growth, as well as survival, settlement, and germination as key indicators of individual recruitment.