Introduction: A successful return to sport (RTS) after anterior cruciate ligament reconstruction (ACL-R) demands optimal physical and psychological rehabilitation. Aim: Study the change in psychological readiness to RTS between three- and six-months post ACL-R, to associate psychological readiness to patient-reported knee function and identify factors associated to greater psychological readiness to RTS. The secondary aim was to examine how the Covid-19 pandemic has affected the patients’ rehabilitation. Methods: Prospective cohort study including patients with primary ACL-R recruited from the Swedish Knee Ligament register, age 16-40 and physically active on Tegner>3. Demographics including pre-injury sport participation, psychological readiness reported with the Anterior Cruciate Ligament-Return to Sport After Injury (ACL-RSI) scale, knee function reported with the subjective International Knee Documentation Committee (IKDC) and the impact on rehabilitation by Covid-19 were analyzed at three- and six-months post-surgery. ACL-RSI scores were compared, correlated to IKDC and univariate analysis was used to determine the association between factors and the psychological readiness to RTS. Results: 141 patients were analyzed (56 men, 85 women; median age 24 years), all were recreational or competitive athletes (median Tegner level 8). The psychological readiness progressed through rehabilitation, was correlated to subjective IKDC. No differences could be detected between ACL-RSI scores and included factors at six months post ACL-R. Covid-19 had an impact on 36% (40/112) of the patients’ rehabilitation. Conclusions: Psychological readiness improved after ACL-R and was significantly associated to self-reported knee function at six months post ACL-R. Covid-19 restrictions affected rehabilitation for one in every three participants.