ABSTRACTTwo novel fluorene functionalized polyacetylenes with different conjugation bridge architectures (stilbene and azobenzene), poly[2‐[4‐vinyl‐4′‐(N‐methyl, N‐ethyl‐yl propargyloxy) phenyl azo]‐9,9‐dioctylfluorene] (PC1), poly[2‐[4‐vinyl‐4′‐(N‐methyl, N‐ethyl‐yl propargyl group) stilbene ethenyl]‐9,9‐dioctylfluorene] (PC2), were designed and prepared through using [Rh(nbd)Cl]2‐Et3N as the catalysts, respectively. These polymers are soluble in common organic solvents, such as toluene, chloroform, 1,2‐dichloromethane, and tetrahydrofuran, which their structures and properties were systematically characterized by means of Fourier transform infrared spectroscopy, nuclear magnetic resonance, elemental analyses, UV–vis, photoluminescence, thermogravimetric analysis, gel permeation chromatography, and Z‐scan technique. The optical limiting properties were investigated at 780 nm with 450 fs laser pulses. Remarkably, it is expected that, by incorporation of fluorene into functional polyacetylene has endowed the resultant polymers with well optical limiting properties and thermal stability. Additionally, the nonlinear optical properties of functionalized polyacetylenes were significantly affected by different molecular structure of conjugated bridge of substituted group. The polyacetylenes with azobenzene (PC2) conjugated bridge displaying well two‐photon absorption cross‐sections of 3950 cm/GM (2010 cm/GM for PC1 containing stilbene), owning to stronger π‐conjugated chromophores of objective polymer and intramolecular charge transfer effect. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46100.