The London, Ont., native finished with 6480 points after the final event, with a season-best time of 2:09.15.
Great Britain's Jessica Ennis captured gold with 6955 points, winning the heat in 2:08.65. Silver went to Russia's Tatayna Chernova and Lyudmyla Yosypenko of Ukraine took bronze.
Brianne Theisen of Humboldt, Sask., finished in 10th place with 6383 points. She raced to a personal best of 2:09.27 to win her 800m heat.
Zelinka entered in eighth place, after posting a personal best of 45.75 metres in the javelin to jump within 198 points of medal contention.
The 30-year-old had a strong first day Friday, clawing back from a poor performance in the high jump in which she placed 19th. She then moved up to 10th place after a personal best of 14.81 metres in the shot put.
Zelinka also posted a personal best time of 23.32 seconds in the in the 200-metre event.