This study, comprising three independent experiments, was conducted to optimize the zinc (Zn) application through seed coating for improving the productivity and grain biofortification of wheat. Experiment 1 was conducted in petri plates, while experiment 2 was conducted in sand-filled pots to optimize the Zn seed coating using two sources (ZnSO4, ZnCl2) of Zn. In the first two experiments, seeds of two wheat cultivars Lasani-2008 and Faisalabad-2008 were coated with 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75 and 2.00 g Zn kg−1 seed using ZnSO4 and ZnCl2 as Zn sources. The results of experiment I revealed that seed coating with 1.25 and 1.50 g Zn kg−1 seed using both sources of Zn improved the seedling emergence. However, seed coated with 1.25 and 1.50 g Zn kg−1 seed using ZnSO4 was better regarding improvement in seedling growth and seedling dry weight. The results of the second experiment indicated that seed coated with 1.25 and 1.50 g Zn kg−1 seed using ZnSO4 improved the seedling emergence and seedling growth of tested wheat cultivars. However, seed coating beyond 1.5 g Zn kg−1 seed using either Zn source suppressed the seedling emergence. Third experiment was carried out in glass house in soil-filled earthen pots. Seeds of both wheat cultivars were coated with pre-optimized treatments (1.25, 1.50 g Zn kg−1 seed) using both Zn sources. Seed coating with all treatments of ZnSO4 and seed coating with 1.25 g Zn kg−1 seed using ZnCl2 improved the seedling emergence and yield-related traits of wheat cultivars. Seed coating with 1.25 g Zn kg−1 seed also improved the chlorophyll a and b contents. Maximum straw Zn contents, before and after anthesis, were recorded from seed coated with 1.5 g Zn kg−1 seed using either Zn source. Increase in grain yield from seed coating followed the sequence 1.25 g Zn kg−1 seed (ZnSO4) >1.25 g Zn kg−1 seed (ZnCl2) >1.5 g Zn kg−1 seed (ZnSO4). However, increase in grain Zn contents from seed coated was 1.5 g Zn kg−1 seed (ZnCl2) >1.25 and 1.5 g Zn kg−1 seed (ZnCl2, ZnSO4) >1.25 g Zn kg−1 seed (ZnSO4). Seed coating with Zn increased the grain Zn contents from 21 to 35 %, while 33–55 % improvement in grain yield was recorded. In conclusion, wheat seeds may be coated with 1.25 g Zn kg−1 seed using either source of Zn for improving the grain yield and grain Zn biofortification.