Ciganda had three of her five birdies in the last six holes as she and Smith took a two-stroke lead.
Ciganda, who won her first LPGA title in South Korea last month, had three of her five birdies in the last six holes as she and Smith took a two-stroke lead over France's Karine Icher, South Korea's Chella Choi and Mexican amateur Maria Fassi.
It was a further stroke back to American Michelle Wie, Colombian Mariajo Uribe and Australian Su Oh on two-under par 70.
"I really like this course, I played good last year so it is great to be back," Ciganda said. "I played pretty solid today, no bogeys, five birdies. I hit it pretty close and I am just looking forward to keeping it going."
Smith had two bogeys and seven birdies, including a birdie at the 18th.
"The last was pretty important to me," she said. "I was sitting in between clubs and I wanted to hit the full shot, and my husband who caddies for me was 'just hit the little one', and I hit the little pass one and I was like maybe I should've hit the full one," Smith said.
"It was kind of one of those things where you play smart, and I was able to put the putt in for birdie so it was good finish. It ended on a high note."
Canadian teenager Brooke Henderson, at seven in the world the highest ranked player in the field, battled to a 74 that included a double bogey at the par-four seventh to go with one bogey and one birdie.
It was an inauspicious start as Henderson tries to bounce back from her worst finish of the year, equal 63rd in Malaysia a fortnight ago.
The tournament is penultimate event of the LPGA season and the last chance for players to qualify for the 72-strong field for next week's Tour Championship in Naples, Florida.
Defending champion Park In-Bee is absent this week with a left thumb injury.