Through the selection of resistance to sparfloxacin, an attenuated Streptococcus agalactiae strain, 138spar, was obtained from its virulent parent strain, S. agalactiae 138P. The full genome of S. agalactiae 138spar is 1,838,126 bp. This genome will allow comparative genomics to identify genes associated with virulence, antibiotic resistance, or other characteristics.