Photo courtesy of Salim Fago's instagram account
The Czech club said the 23-year-old center forward, who can also be used as a winger, had penned a three-and-a-half-year contract.
Lawal has scored seven goals this season in his 19 games for Istra in the Croatian league and cup.
Financial details were not disclosed but Viktoria reportedly paid 2.4 million euros ($2.9 million) for Lawal, who was in the Nigeria team that claimed the bronze medal at this year's Africa Cup of Nations in Morocco.
Viktoria has reached the knockout stage of the Europa League.
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