We present a new catalog of HII regions in M31. The full disk of the galaxy (∼24 kpc from the galaxy center) is covered in a 2.2 deg 2 mosaic of 10 fields observed with the Mosaic Camera on the Mayall 4 m telescope as part of the Local Group Galaxies survey. We used HIIphot, a code for automated photometry of HII regions, to identify the regions and measure their fluxes and sizes. A 10σ detection level was used to exclude diffuse gas fluctuations and star residuals after continuum subtraction. That selection limit may result in missing some faint HII regions, but our catalog of 3691 HII regions is still complete to a luminosity of L Hα = 10 34 erg s −1 . This is five times fainter than the only previous CCD-based study which contained 967 objects in the NE half of M31. We determined the Hα luminosity function (LF) by fitting a power law to luminosities larger than L Hα = 10 36.7 and determined a slope of 2.52±0.07. The in-arm and inter-arm LFs peak at different luminosities but they have similar bright-end slopes. The interarm regions are less populated (40% of total detected regions) and constitute only 14% of the total luminosity of L Hα = 5.6 × 10 40 erg s −1 (after extinction correction and considering 65% contribution from diffused ionized gas). A star formation rate of 0.44 M ⊙ yr −1 was estimated from the Hα total luminosity; this value is consistent with the determination from the Spitzer 8 µm image. We removed all known and potential planetary nebulae, yet we found a double peaked luminosity function. The inter-arm older population suggests a starburst between 15 and 20 million years ago. This result is in agreement with UV studies of the star formation history in M31 which found a star formation rate decrease in the recent past. We found a fair spatial correlation between the HII regions and stellar clusters in selected star forming regions. Most of the matched regions lie within the arm regions.