Kasatkina was fresh off a promising run to the last 16 at Roland Garros last week, and her weekend engagement to long-term partner Natalia Zabiiako, a former Olympic skater.
But her joy was soured, temporarily at least, as Kartal delighted the home crowd in the first women's tournament at Queen's in more than 50 years.
In the last final, in 1973, Evonne Goolagong (now Cawley) lost to Russia's Olga Morozova, who would go on to lose that year's Wimbledon final a few weeks later.
That was the fourth successive final featuring an Australian, Margaret Court having won in 1970 and 1971 and Karen Krantzcke losing to Chris Evert in 1972.
Any hopes that Kasatkina would maintain the Aussie run 52 years on soon disappeared against Kartal, who has climbed from 271st in the world to 50th in a year.
This was the 23-year-old's best win of her career, the world No 16 Kasatkina becoming her second top-20 victim after beating Beatriz Haddad Maia at Indian Wells.
Kasatkina briefly hinted at battling back when she rallied from 0-40 at 2-4 in the final set to force deuce, but on the newly-christened Andy Murray Arena Kartal held for 5-2, then served out at 5-3, her winning forehand leaving Kasatkina flat-footed.
The result left two Australians in the draw, Ajla Tomljanovic and Maddison Inglis.
Inglis drew No.6 seed Karolina Muchova and was last on court on Monday evening. She lost the first set on a tie-beak 7-6 (7-5) but battled back to take the second set 6-3. At that point, with darkness falling, play was suspended.
The winner will meet German qualifier Tatjana Maria, who beat former US Open runner-up Leylah Fernandez 7-6 (7-4) 6-2.
On Tuesday Tomljanovic plays Alex de Minaur's fiancee Katie Boulter, who earlier teamed up with Emma Raducanu in a doubles pairing that had the British media swooning as they won their first round match.
In the day's opening match Haddad Maia came from a set down to beat former Wimbledon champion Petra Kvitova 2-6 6-4 6-4.
Two-time Wimbledon winner Kvitova, 35, returned from a 17-month maternity break in February but has only won one match since.
Last year's Wimbledon semi-finalist and Olympic runner-up Donna Vekic lost 6-3 6-3 to Anastasia Zakharova who set up a clash against American Madison Keys.
