The differences and relationship between joint stiffness and leg stiffness can be used to characterize the lower limb behavior during different walking speeds. This study aimed to investigate the differences in whole leg and lower limb joint stiffness at different walking speeds and the interactions between leg and lower limb joint stiffness. Twenty-seven healthy adults, seventeen males (age: 19.6 ± 2.2 years, height: 176.0 ± 6.0 cm, mass: 69.7 ± 8.9 kg), and ten females (age: 19.1 ± 1.9 years, height: 164.0 ± 3.0 cm, mass: 59.6 ± 3.8 kg), were recruited. Dynamic leg and joint stiffness were calculated during eccentric loading from data recorded using 3D infrared motion analysis and force plates at slow, normal, and fast walking speeds. Differences in dynamic stiffness, joint angles and moments were explored between the walking speeds using Repeated Measures ANOVA with Sidak post-hoc tests. Correlations between leg, joint stiffness, and walking speed were also explored. The results indicated that the leg dynamic stiffness is decreased by walking speed, however, hip and ankle joint stiffness were increased (p < 0.001) and knee stiffness was unaffected. Leg stiffness showed no correlation with hip, knee, or ankle stiffness. A positive significant correlation was seen between hip and ankle stiffness (p < 0.01) and between knee and ankle stiffness (p < 0.001), however, no correlation was seen between hip and knee stiffness. These results suggest leg stiffness is not associated with lower limb joint stiffness during eccentric loading. This provides new information on the responses of ankle, knee and hip joint stiffness to walking speed.