David Pearson, 52, told officers he killed his girlfriend at their apartment in the 9200 block of Topanga Canyon Boulevard.
When police arrived at the home, they found the body of Kristen Hyde. Detectives believe Hyde, 62, was strangled.
They arrested Pearson for the crime. His was being held on $1 million bail.
Authorities have not determined a motive for the crime.
Anyone with information was urged to call police at (877) LAPD-24-7.