We study holographic duals of type II and heterotic matrix string theories described by warped AdS 3 supergravities. By explicitly solving the linearized equations of motion around near horizon D-string geometries, we determine the spectrum of Kaluza-Klein primaries for type I, II supergravities on warped AdS 3 × S 7 . The results match those coming from the dual two-dimensional gauge theories living on the D-string worldvolumes. We briefly discuss the connections with the N = (8, 8), N = (8, 0) orbifold superconformal field theories to which type IIB/heterotic matrix strings flow in the infrared. In particular, we associate the dimension (h,h) = ( 3 2 , 3 2 ) twisted operator which brings the matrix string theories out from the conformal point (R 8 ) N /S N with the dilaton profile in the supergravity background.The familiar dictionary between masses and "scaling" dimensions of field and operators are modified by the presence of non-trivial warp factors and running dilatons. These modifications are worked out for the general case of domain wall/QFT correspondences between supergravities on warped AdS d+1 × S q geometries and super Yang-Mills theories with 16 supercharges.