Romero finished at 11-under 202, good for his fifth victory on the Champions Tour. The 54-year-old Argentine won $255,000.
Sindelar fired an 8-under 63, the best round of the tournament, and O'Meara carded a 70 to tie for second place at 10-under 203.
Romero put together three straight birdies at Nos.10, 11 and 12 to take the lead and then added another birdie at 15.
Tim Simpson (67), David Eger (68), Fred Funk (69) and Tom Jenkins (69) shared fourth place at 8-under 205.