This study investigated the acute effects of repeated walking sessions within green and suburban environments on participants' psychological (anxiety and mood) and cognitive (directed-attention) outcomes. Twenty-three middle-aged adults (19 female) participated in a non-randomized crossover study comprised of once-weekly 50-min moderate-intensity walking sessions. Participants walked for three weeks in each of two treatment conditions: green and suburban, separated by a two-week washout period. Eleven participants completed green walking first and 12 suburban walking first. For each walk, we used validated psychological questionnaires to measure pre- and post-walk scores for: (1) mood, evaluated via the Positive and Negative Affect Schedule (PANAS); (2) anxiety, assessed by the State-Trait Anxiety Inventory (STAI-S); and (3) directed-attention, measured using the visual Backwards Digit Span test (BDS). Repeated measures linear mixed models assessed pre- to post-walk changes within-treatment conditions and post-walk contrasts between-treatment conditions. Results indicated that anxiety decreased after green walking and increased after suburban walking (-1.8 vs. +1.1 units, respectively; = 0.001). For mood, positive affect improved after green walking and decreased after suburban walking (+2.3 vs. -0.3 units, respectively; = 0.004), and negative affect decreased after green walking and remained similar after suburban walking (-0.5 vs. 0 units, respectively; = 0.06). Directed-attention did not improve from pre- to post-walk for either condition. Our results suggested that green walking may be more effective at reducing state anxiety and increasing positive affect compared to suburban walking.