Salt stress is major constraint affecting agricultural productivity, land degradation and has become a serious threat for global food security. The selection and evaluation of barley genotypes that can tolerate salt stress are the main components for rehabilitation of salt-degraded marginal soils in arid and semi-arid countries, including Arabian Peninsula. A field experiment was conducted to evaluate the response of six barley genotypes (62/3 A, 76/2 A, N2–35, N2–4, Badia, Furat1) at three salinity levels (0, 7 and 14 dS m⁻¹) to evaluate the response of genotypes based on morpho-physiological characteristics and nutrients uptake. The grain yield stability (static environmental variance (S²) and dynamic Wricke’s ecovalence (W²), and harvest index (HI) was also estimated. The higher salinity treatment (14 dS m⁻¹) resulted in devastating reduction in barley yield traits. Additionally, salt treatments (7 dS m⁻¹, 14 dS m⁻¹), genotypes and interaction between (genotypes ∗ salinity levels) exhibited significant (p < 0.001) differences. The genotype N2–35 exhibited highest plant biomass, grains per spike and grains per plant, whereas the genotype 76/2 A resulted in lowest number of grains per spike and grains per plant. The highest K⁺ was noticed from Badia genotype, whereas the 62/3 A genotype failed to accumulate K⁺. The genotype, Furat1, showed substantial amount of Cl^- and Na⁺ contents followed by Badia. Except Badia and N2–35, all other genotypes showed higher Δ¹³C values. The Badia genotype also showed higher iWUE compared to all other genotypes. Contrarily the genotypes N2–4 and 62/3 A exhibited maximum reduction in iWUE. The δ¹⁵N trait increased following salinity treatment. Genotypes N2–35 and N2–4 showed highest δ¹⁵N while 62/3 A and 76/2 A exhibit lowest values for δ¹⁵N. The study exhibited that the genotype N2–35 was tolerant to salinity stress whereas the response of Furat1 genotype suggested salt susceptible behaviour. It was concluded that salt tolerant genotype can be cultivated in saline marginal soils for food security and help in rehabilitation of marginal lands.