Emission spectra and decay properties of the 4 G 5/2 level of Sm 3+ ions in LaMgAl 11 O 19 :Sm 3+ (LMA:Sm 3+ ) have been measured as functions of pressure up to 100 kbar at room temperature. Changes of the positions of three considered fluorescence lines (560, 606, and 643 nm) under pressure are very small. The fourth one (594 nm) is practically insensitive upon pressure and has a red shift rate (RSR) close to zero. Fluorescence lifetime τ for the 594 nm line decreases non-linearly with pressure in the considered pressure range. Effect of the pressure on τ was described using a model which considered the change of the inter-ionic distance (r), ionic polarizability (α), and material refractive index (n) with pressure. Calculated pressure-induced change of the lifetime τ is in good agreement with the experimental data. Insensitivity of the lines position upon the pressure, and small RSR, leads to conclusion that LMA:Sm 3+ can be the base for a new generation of solid state lasers with numerous applications.