Leicester Crown Court heard that Collins was pulling the metal cage overloaded with 230 kg of paint out from an uneven lift floor at the store's Beaumont Shopping Centre branch when it toppled on her, causing a severe spinal fracture.
Leicester City Council's public safety team, which brought the prosecution, described it as a "high culpability case". No suitable risk assessments had been carried out and the general risk assessment covering roll cages did not cover the hazards involved in maneuvering them on uneven surfaces.
The court also heard that employees had not been given information on the safe distribution of loads throughout roll cages, nor adequate training in their use. Wilco provided no proper supervision.
Wilko Retail, which is based in Worksop, Nottinghamshire, has nearly 400 stores across the UK, including four in Leicester, and a £1.4bn turnover. The firm previously pleaded guilty to four offences under the Health and Safety at Work Act.
Passing sentence today, Judge Ebraham Mooncey imposed the £2.2m fine for the first of the four offences: failing to ensure the health, safety and welfare of employees. The company was also ordered to pay £70,835 in costs.
Collins, who had just completed the first year of a degree at Northampton University, spent weeks at Coventry's Walsgrave Hospital following the accident before being transferred to the spinal injuries unit at Sheffield for extensive rehabilitation. She was discharged in December 2013, 18 months after her injury, and returned part-time to her university course.