Abstract A series of β‐SiAlON:Eu 2+ phosphors were synthesized from single‐source precursors, perhydropolysilazane chemically modified with Al(OCH(CH 3 ) 2 ) 3 , AlCl 3 , and EuCl 2 . The single‐source precursors were converted to β‐SiAlON:Eu 2+ phosphors by pyrolysis under flowing N 2 or NH 3 at 1000°C, followed by heat treatment at 1800°C under an N 2 gas pressure at 980 kPa. By varying the molar ratio of the chemical modifiers, β‐SiAlON:Eu 2+ with the compositions close to the theoretical ones expressed as Si 6− z Al z O z −2 y N 8− z +2 y : y Eu 2+ were synthesized, where the z values and Eu 2+ contents were controlled in the ranges of .44–.78 and .35–1.48 mol%, respectively. The polymer‐derived β‐SiAlON:Eu 2+ phosphors exhibited green emission under excitation at 460 nm attributed to the 4f 7 –4f 6 (7f 3 )5d 1 transition of dopant Eu 2+ . High‐angle annular dark‐field‐scanning transmission microscopy analysis confirmed that the doped‐Eu 2+ existed interstitially within the channels along the c axis of host β‐SiAlON. Compared with the conventional powder metallurgy route, the polymer‐derived ceramic route in this study offers some advantages in the grain growth of host β‐SiAlON and photoluminescence properties in terms of green emission intensity under excitation at 460 nm, and the highest intensity was achieved for the polymer‐derived β‐SiAlON:Eu 2+ with z = .64 and .37 mol% Eu 2+ .