© 2014 American Physical Society. We present measurements of the absolute photoionization cross section of the aluminumlike Si+ ion over the 94-137 eV photon energy range. The measurements were performed using the merged-beam setup on the PLEIADES beamline at the SOLEIL synchrotron radiation facility. Signals produced in the Si2+ and Si3+ photoionization channels of the 2p subshell of the Si+ ion from both the 1s22s22p63s23p2P1/2,3/2 ground levels and the 1s22s22p63s3p24P metastable levels were observed. Absolute cross sections were determined. Calculations of the 2p inner-shell photoionization cross sections were carried out using the multiconfiguration Dirac-Fock and Dirac-Coulomb R-matrix theoretical approaches and are compared with experiment.