What was the net revenue for the fourth quarter of 2020 
nsion from terminal sales to user operations. All of this product and technology innovation, IoT experience, as well as the service optimization are the key drivers of our long-term development. The construction of China's 5G infrastructure has demonstrated rapid development. An era of the commercial application of IoT is on the way.
According to data released by IDC, 85% of devices will be connected to the Internet and 15% will be connected to IoT by 2022. It was pointed out in the guidelines for construction of the National AI Standards System, launched by the Ministry of Industry and Information Technology and other national official departments in last July that smart home product and application will be promoted as one of the important industries in this area. We believe that with the rapid application of 5G and the continuous improvement of smart home ecology, IoT will be applied in more and more home scenarios. We are confident in our leading position in this industry, as well as our capabilities to deliver robust and stable growth while maintaining a healthy level of profitability, bringing long-term value to our shareholders.
That concludes our founder's remarks. Let's now turn to the detailed financial review of the fourth-quarter 2020, as well as the outlook for the first-quarter 2021. The net revenues were RMB 1.89 billion, representing year-over-year increase of 8.5%. The growth was slightly below our previous guidance by just around 0.6% primarily due to the proactive step to stop the sales of some specific products with lower average selling prices and lower gross margins, such as some low-end refrigerators and washing machines, in order to make room for the launch of a slate of new large-screen refrigerators and high-end washing machines, as well as to improve the profitability.
Revenues from IoT @ Home portfolio increased by 15.7% to RMB 1.11 billion from RMB 963.7 million for the fourth quarter of 2019, primarily driven by the sustained sales increase for certain new product categories, in particular, our sweeper robots. Viomi-branded sweeper robot business is expected to make greater contribution in 2021. Revenues from our home water solutions decreased by 5.9% to RMB 363 million. The decline was primarily due to the decreases in the average selling prices of our Xiaomi-branded water purifiers products.
This was partially offset by the successful introduction and increased sales of our new series of Viomi-branded water purifier products, which narrowed the year-over-year decline for home water solutions compared to the previous quarter. Viomi-branded water purifiers are expected to make greater contribution in our home water solution business, as well as our total net revenues in 2021. Revenues from consumables increased by 69.3% to RMB 160.2 million primarily due to increased demand for our water purifier filter products. Revenues from small appliances and others decreased by 15.5% to RMB 251.2 million primarily due to product portfolio optimization for higher gross margin in this category.
Gross profit increased by 28% to RMB 443.8 million, and gross margin was 23.5% compared to 17.1% for the third quarter of last year and 19.9% for the fourth quarter of 2019. The quarter-over-quarter and year-over-year increases in gross margin were primarily driven by our efforts to shift the business and product mix toward higher gross margin products, including the rollout of our new Viomi-branded water purifiers and sweeper robots, alongside the optimization of margins across product lines. As Mr. Chen discussed, the meaningful recovery in gross margin was in line with our quality growth strategy, demonstrating our business flexibility and strong execution capabilities.
As we continue to phase out our lower-margin products and focus our efforts on generating greater revenue contribution from higher-margin product categories and SKUs, we do expect to experience not full degree of gross margin recovery in 2021. The total operating expenses increased by 21.3% to RMB 331.8 million primarily due to the growth of our 
nsion from terminal sales to user operations. All of this product and technology innovation, IoT experience, as well as the service optimization are the key drivers of our long-term development. The construction of China's 5G infrastructure has demonstrated rapid development. An era of the commercial application of IoT is on the way.
According to data released by IDC, 85% of devices will be connected to the Internet and 15% will be connected to IoT by 2022. It was pointed out in the guidelines for construction of the National AI Standards System, launched by the Ministry of Industry and Information Technology and other national official departments in last July that smart home product and application will be promoted as one of the important industries in this area. We believe that with the rapid application of 5G and the continuous improvement of smart home ecology, IoT will be applied in more and more home scenarios. We are confident in our leading position in this industry, as well as our capabilities to deliver robust and stable growth while maintaining a healthy level of profitability, bringing long-term value to our shareholders.
That concludes our founder's remarks. Let's now turn to the detailed financial review of the fourth-quarter 2020, as well as the outlook for the first-quarter 2021. The net revenues were RMB 1.89 billion, representing year-over-year increase of 8.5%. The growth was slightly below our previous guidance by just around 0.6% primarily due to the proactive step to stop the sales of some specific products with lower average selling prices and lower gross margins, such as some low-end refrigerators and washing machines, in order to make room for the launch of a slate of new large-screen refrigerators and high-end washing machines, as well as to improve the profitability.
Revenues from IoT @ Home portfolio increased by 15.7% to RMB 1.11 billion from RMB 963.7 million for the fourth quarter of 2019, primarily driven by the sustained sales increase for certain new product categories, in particular, our sweeper robots. Viomi-branded sweeper robot business is expected to make greater contribution in 2021. Revenues from our home water solutions decreased by 5.9% to RMB 363 million. The decline was primarily due to the decreases in the average selling prices of our Xiaomi-branded water purifiers products.
 This was partially offset by the successful introduction and increased sales of our new series of Viomi-branded water purifier products, which narrowed the year-over-year decline for home water solutions compared to the previous quarter. Viomi-branded water purifiers are expected to make greater contribution in our home water solution business, as well as our total net revenues in 2021. Revenues from consumables increased by 69.3% to RMB 160.2 million primarily due to increased demand for our water purifier filter products. Revenues from small appliances and others decreased by 15.5% to RMB 251.2 million primarily due to product portfolio optimization for higher gross margin in this category.
Gross profit increased by 28% to RMB 443.8 million, and gross margin was 23.5% compared to 17.1% for the third quarter of last year and 19.9% for the fourth quarter of 2019. The quarter-over-quarter and year-over-year increases in gross margin were primarily driven by our efforts to shift the business and product mix toward higher gross margin products, including the rollout of our new Viomi-branded water purifiers and sweeper robots, alongside the optimization of margins across product lines. As Mr. Chen discussed, the meaningful recovery in gross margin was in line with our quality growth strategy, demonstrating our business flexibility and strong execution capabilities.
As we continue to phase out our lower-margin products and focus our efforts on generating greater revenue contribution from higher-margin product categories and SKUs, we do expect to experience not full degree of gross margin recovery in 2021. The total operating expenses increased by 21.3% to RMB 331.8 million primarily due to the growth of our 