Consolidated revenues increased 11.1% year-over-year in our first full quarter as a stand-alone public company.
The revenue increase included same-store revenue growth of 14.8% and we reported adjusted EBITDA margin that improved to 15.4% of revenues.
We have enhanced digital payment platforms that are enabling over 75% of monthly customer payments to be made outside of our stores.
We have an industry-leading, fully transactional e-commerce platform that is attracting a new and younger customer, and we have a portfolio of 51 GenNext stores that is currently outperforming our expectations with many more store openings in the pipeline.
We are encouraged by the continuing improvement and the quality and size of our same-store lease portfolio, which ended the quarter up 6.2% compared to the end of the first quarter of 2020.
Today, nearly 70% of our portfolio is made up of lease agreements that were originated using this technology.
Another contributor to our strong performance in the quarter was our e-commerce channel, which represented more than 14% of lease revenues.
Our e-commerce team has really delivered, driving traffic growth to aarons.com by 12.8% and increasing revenues by 42% in the first quarter as compared to the prior-year quarter.
In addition, e-commerce write-offs improved by more than 50% compared to last year's quarter, primarily as a result of ongoing decisioning optimization, operational enhancements, and strong customer payment activity.
To date, we have opened 51 new GenNext stores and have generated results that are meeting or exceeding our targeted internal rate of return equally as encouraging, monthly lease originations in the first quarter.
For the first quarter of 2021, revenues were $481.1 million compared to $432.8 million for the first quarter of 2020, an increase of 11.1%.
The increase in revenues was primarily due to the improving quality and increased size of our lease portfolio and strong customer payment activity during the quarter, aided in part by government stimulus and partially offset by the net reduction of 166 Company-operated and franchised stores compared to the prior year.
As Douglas called out earlier, e-commerce revenues were up 42% compared to the first quarter of the prior year and represented 14.2% of overall lease revenues compared to 11.3% in 2020.
On a same-store revenue basis, revenues increased 14.8% in the first quarter compared to the prior-year quarter, the first double-digit, same-store revenue growth since 2009, and our fourth consecutive positive quarter.
Additionally, the company ended the first quarter of 2021 with a lease portfolio size for all company operated stores of $128.8 million, an increase of 3.6% compared to the lease portfolio size as of March 31, 2020.
Operating expenses excluding restructuring expenses, spin-related transaction costs and the impairment of goodwill and other expenses, which were both recorded in the first quarter of 2020 were down $1.5 million as compared to the first quarter of last year.
Adjusted EBITDA was $73.9 million for the first quarter of 2021 compared with $34.7 million for the same period in 2020, an increase of $39.2 million or 112.9%.
As a percentage of total revenues, adjusted EBITDA was 15.4% in the first quarter of 2021 compared with 8% for the same period last year, an improvement of 740 basis points.
The improvement in adjusted EBITDA margin was primarily due to the items that drove the total revenues increase and a 310 basis point reduction in overall write-offs to 3.1% of lease revenues, including both improvement in the e-commerce and store origination channels compared to the prior year.
On a non-GAAP basis, diluted earnings per share were $1.24 in the first quarter of 2021 compared to non-GAAP diluted earnings per share of $0.30 for the same quarter in 2020, an increase of $0.94 or 313.3%.
Cash generated from operating activities was $20.2 million for the first quarter of 2021, a decline of $36.6 million compared to the first quarter of 2020, primarily due to higher inventory purchases, partially offset by higher customer payments and other changes in working capital.
During the quarter, the company purchased 252,200 shares of Aaron's common stock for a total purchase price of approximately $6.3 million.
As of the end of the quarter, we had approximately $143.7 million remaining under the company's share repurchase authorization that was approved by our Board on March 3rd of this year.
The Company's Board of Directors also declared our first quarterly cash dividend of $0.10 per share last month and we paid the dividend on April 6.
As of March 31, 2021 the company had a cash balance of $61.1 million, less than $500,000 of debt and total available liquidity of $295.5 million.
For the full year, we expect consolidated revenues of between $1.725 billion and $1.775 billion representing an increase in our revenue outlook of $75 million.
We also expect adjusted EBITDA of between $190 and $205 million, representing an increase in our adjusted EBITDA outlook of $35 million.
We have also increased our full-year same-store revenue outlook from a range of 0% to 2% to a range of 4% to 6%.

Summary:
For the first quarter of 2021, revenues were $481.1 million compared to $432.8 million for the first quarter of 2020, an increase of 11.1%.
On a non-GAAP basis, diluted earnings per share were $1.24 in the first quarter of 2021 compared to non-GAAP diluted earnings per share of $0.30 for the same quarter in 2020, an increase of $0.94 or 313.3%.
For the full year, we expect consolidated revenues of between $1.725 billion and $1.775 billion representing an increase in our revenue outlook of $75 million.