Steels with high strength and high hardness are considered to be the essential criteria for weight reduction in armored fighting vehicles (AFVs). Ultrahigh hard armor (UHA) steels are higher hardness (>500 HV) and higher strength (>1,500 MPa) than the currently used rolled homogenous armor (RHA) steels. The occurrence of both a tempered region in the grain-refined heat-affected zone (HAZ) and hydrogen-induced cracking (HIC) has become the limiting factor in the life extension of weld in high-strength and high-hardness armor grade steels. Hence, an attempt was made to weld UHA steel by gas metal arc welding (GMAW) process using different three filler metals (1) austenitic stainless steel (ASS), (2) duplex stainless steel (DSS), and (3) low-hydrogen ferritic. The ballistic performance of the joints was evaluated based on the area density and depth of penetration. The mechanical properties (transverse tensile, hardness, and impact toughness) and microstructural features of welded joints are correlated with the ballistic performance. All the joints stopped the 7.62 × 51 ball projectile at the weld metal region. However, through-hole (perforation) was observed when tested against the 7.62 × 54 armor piercing projectile. The joints fabricated using ASS filler wire showed superior ballistic resistance, a lesser degree of HAZ softening, and better impact toughness properties due to the higher energy absorption capability of the austenitic phase.