<p>Organic materials with luminochromic properties exhibit changes in their luminescent characteristics in response to alterations in environmental factors and have attracted attention as a platform because of their applicability in luminescent sensors. A series of boron pyridylenolate complexes is a promising candidate for luminochromic dyes. It has been reported that some π-conjugated polymers composed of the boron pyridylenolate complexes exhibited luminochromic behaviors induced by mechanical forces or temperature changes. However, the generality of the mechanisms and structure–property relationships of those chromic behaviors has still been veiled. Herein, we report the solution-state thermochromic luminescence of the boron pyridylenolate polymer and the effects of the steric structure on the boron atom. The mechanistic study clarified that the solution-state luminochromic properties should be derived from the changes in intermolecular interactions. In addition, we demonstrate that the combined use of this polymer and a hyperspectral camera enables the visualization of temperature distributions within fluid samples.</p>