During the investigation of a solid‐solution series between the alkali lithosilicate Na[Li3SiO4] and the hypothetical nitridolithoaluminate Eu[LiAl3N4] with the generalized sum formula Na1-xEux[Li3-2xSi1‐xAl3xO4-4xN4x], a hitherto unknown oxo‐nitride has been synthesized. The new material with the composition Na1-xEux[Li3-2xSi1‐xAl3xO4-4xN4x] (x = 0.22) crystallizes in the tetragonal space group I4/m (no. 87) with a = 7.704(2) and c = 3.1584(6) Å. To the best of our knowledge this is the first synthesis of a litho‐alumo‐oxo‐nitridosilicate containing either alkali‐, or rare‐earth metals. Upon excitation of this novel compound with near UV to blue light, a broadband amber emission with a maximum at 612 nm and a full width at half maximum of 2835 cm‐1 (≈ 105 nm) is observed. Furthermore, single‐crystals of the solid‐solution series could be synthesized on the oxygen‐rich side between 0 < x < 0.2. The thereby received phosphors crystallize in the Na[Li3SiO4]‐structure type and their emission maxima can be shifted in the spectral range from 469 nm up to 588 nm.