The 38-year-old American brought her experience to bear from the second set to seal a comfortable win in her first meeting with the Romanian.
"It's just credit to her, she played very well and took advantage, you have to at these championships," Venus said of Dulgheru's first-set performance.
"It's not easy to play someone you haven’t played, and I’m sure she’s seen me play a lot, so she was extremely competitive," she added.
Dulgheru, world number 141, came out fighting in the deciding set, won her serve and had two break points for the second game, only for Venus to save both and hold.
Asked about her improved performance from the second set and whether it confirmed her form as she seeks a second consecutive final and sixth title, she said: "It's just about winning a match, whether it's your best (tennis) or not doesn't matter."
(Reporting by Rex Gowar, editing by Ed Osmond)
