<p>Using tubular thin-walled structures as lateral energy absorbers has recently attracted significant attention. This study presents and investigates novel auxetic energy absorbers under lateral loading through both numerical and experimental methods. To this end, three auxetic structures—re-entrant, chiral, and anti-chiral—were selected for analysis. Additionally, a simple energy absorber and a hexagonal energy absorber were included to provide a comparative understanding of auxetic behavior. Two performance criteria were employed to evaluate the proposed energy absorbers: energy absorbed (EA) and specific energy absorbed (SEA). Initially, the absorbers were optimized using a genetic algorithm. A comparison of the optimized auxetic structures with the hexagonal absorber revealed the following: the optimized anti-chiral absorber increased EA and SEA by 1.7 and 1.5 times in the pre-densification stage and by 2.1 and 2.0 times, respectively, in the densification stage. The optimized chiral absorber increased EA and SEA by 1.5 times each in the pre-densification stage and by 1.4 and 1.5 times, respectively, in the densification stage. The optimized re-entrant absorber increased EA and SEA by 1.1 and 1.21 times in the pre-densification stage, and by 1.2 and 1.5 times, respectively, in the densification stage. Subsequently, a parametric study was conducted to examine the influence of geometric parameters on energy absorption in auxetic structures. Finally, the optimized re-entrant and anti-chiral absorbers, along with the simple absorber, were fabricated using 3D printing and subjected to experimental testing. The results of the simulations and experiments were in acceptable agreement.</p>