Prabha Arun Kumar was found dead on a footpath in Parramatta Park, in Sydney's west, on March 7, 2015.
The 41-year-old was on the phone to her husband Arun in India when she was stabbed in the neck, with Mr Kumar reportedly hearing his wife confronted by her attacker.
The NSW government and police announced the reward on Monday for anyone who could provide information that led to the arrest and conviction of the killer.
Mr Kumar, who lived in Bangalore with the couple's daughter, flew into Australia when he learned of his wife's death.
She was only weeks away from moving back to India because she missed her family members.
"My wife was the most caring and beautiful soul," Mr Kumar said at the time.
Ms Kumar, who lived about 300m from where she was killed, moved to Australia in 2012 for a project with tech firm Mindtree.
Police said they had pursued multiple lines of inquiry and made several public appeals for information but the case remains unsolved.
Investigators previously dismissed the prospect of the attack being racially motivated.
Speaking in the days after the stabbing, then-NSW premier Mike Baird assured the Indian community authorities would find the killer.
"The people of NSW have a very strong affinity for India and its people and I want to reassure the people of India that the NSW government is treating this investigation with the highest possible priority," he said at the time.
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