People commonly cope with chronic low back pain (cLBP) by ignoring and distraction. Can mindful interoceptive exposure to the pain sensation itself and its phenomenological components be an alternative approach? Single-arm feasibility study in patients with cLBP using a 2-minute attention exercise guided by a smartphone app several times per day over 8 weeks. We assessed feasibility, pre/post pain, function, and psychological parameters using mixed methods: standard questionnaires, ecological momentary assessment, and exit interviews that included micro-phenomenology technique and subsequent reflexive thematic qualitative analysis. We enrolled 31 participants, mostly female, mean age 48, the majority had pain for >5 years; 29 completed. Mean pain intensity [0-10] improved from 4.8 ±1.7 to 3.1 ±1.9 (p < .0001); mean PEG scores (intensity and interference with daily life; range 0-30) improved from 13.7 ±6.2 to 8.4 ±6.6 (p < .0001); pain impact (9 items incl physical function) 22.3 ±8.7 to 19.7 ±8.1 (p = .0010). Twenty-one of 29 improved PEG score ≥30%. There were significant improvements in PCS Rumination and MAIA Not-Worrying. Participants became aware of their usual habit of avoidance and the challenge of and resistance to focusing on pain. They were surprised how pain sensations varied over time, and that pain intensity and the threat value of pain could diminish by focusing on it. They described a variety of 3D pain shapes (e.g., football, pool ball, rod, nail, brick, stars) with a range of colors, transparency, temperature, and density that for some changed with mindful attention. Most struggled to find appropriate words for sensory awareness and attention regulation and found that the threat value of their pain diminished. Mindful interoceptive exposure to the sensations of their cLBP using a 2-minute attention exercise with a phone app-rather than ignoring and distracting from it-may be a beneficial intervention for cLBP. ClinicalTrials.gov #NCT06186193.