What was the revenue for Skyworks in the fourth fiscal quarter of 2021 
ins in wireless infrastructure.
Specifically, in mobile, we accelerated the reach of our Sky5 portfolio, powering the latest launches at leading Tier 1 smartphone OEMs supporting more than 20 platforms. In addition, we shipped Sky5 solutions across Samsung Galaxy's tablet portfolio. In IoT, we continue to gain new customers and expand content. We delivered 5G CPE connectivity solutions to Nokia.
We partnered with Swisscom to launch their WiFi 6 GPON residential gateway. We ramped WiFi 6 and 6E platforms at NETGEAR and Cisco. Launched connectivity and home security devices with Amazon, Ring, and Comcast and captured design wins at Garmin supporting mobile fitness applications. In automotive, we supported autonomous driving systems with a market-leading Robotaxi platform and enabled advanced Charge Control Unit systems for a Tier 1 European automotive OEM.
Across the infrastructure markets, we provided power isolation solutions to a strategic manufacturer of EV including residential solar and energy storage systems, and we secured multiple design wins in next-generation MIMO and small cell base station installations. Moving ahead, we see a multiyear secular technology evolution with our aperture widening from smartphones to industrial, automotive, and an expansive set of IoT devices. Skyworks is fueling this dramatic technological shift with our unique capabilities, integrating not only 5G, but increasingly with our other critical connectivity protocols, including high-performance Wi-Fi, Bluetooth, and precision GPS. As these opportunities emerge, Skyworks is positioned to win.
With the breadth and depth of our customer relationships established over 20 years, our experience across multiple technology transitions, and a dedicated and talented workforce that executed extraordinarily well during fiscal 2021. With that, I will turn the call over to Kris.
Kris Sennesael -- Chief Financial Officer
Thanks, Liam. Skyworks revenue for the fourth fiscal quarter of 2021 was $1.311 billion, up 17% sequentially and up 37% year over year, driven by both mobile solutions and broad markets. Gross profit in the fourth quarter was $668 million, resulting in a gross margin of 51% up 40 basis points sequentially and 60 basis points year over year. Operating expenses were $180 million or 13.8% of revenue, demonstrating leverage in our operating model while continuing our strategic investments in support of future growth.
We generated $488 million of operating income, translating into an operating margin of 37.2%. We incurred $11 million of other expenses, and our effective tax rate was 8%, driving net income of $439 million. So, top-line momentum and execution on margins drove diluted earnings per share of $2.62 ahead of consensus estimates. EPS grew 22% sequentially and increased 42% compared to Q4 of last year.
Turning to the balance sheet and cash flow. Fourth fiscal quarter cash flow from operations was $398 million. Capital expenditures were $263 million, and we paid $93 million in dividends and repaid $250 million of our term loan. Let's also review our record-breaking full fiscal year performance.
Revenue grew 52% to $5.1 billion, adding over $1.7 billion in incremental revenue over fiscal 2020. Gross profit was $2.6 billion, resulting in a gross margin of 50.9%. Operating income increased 73% to $2 billion with an all-time record operating margin of 38.2%, up 450 basis points from the prior year. Net income was $1.8 billion, translating into $10.50 of diluted earnings per share, up 71% year over year.
Cash flow from operations was up 47% to $1.8 billion. And during fiscal 2021, we returned $536 million of cash back to the shareholders with $340 million in dividends and $196 million in share buybacks, all during Q1 of fiscal '21. Starting in Q2 of fiscal '21, we temporarily suspended our share repurchase program in connection with the acquisition of the Infrastructure & Automotive business from Silicon Labs. Given the strength of our business and the progress we have made on integrating the acquisition and given the low leverage ratio 
ins in wireless infrastructure.
Specifically, in mobile, we accelerated the reach of our Sky5 portfolio, powering the latest launches at leading Tier 1 smartphone OEMs supporting more than 20 platforms. In addition, we shipped Sky5 solutions across Samsung Galaxy's tablet portfolio. In IoT, we continue to gain new customers and expand content. We delivered 5G CPE connectivity solutions to Nokia.
We partnered with Swisscom to launch their WiFi 6 GPON residential gateway. We ramped WiFi 6 and 6E platforms at NETGEAR and Cisco. Launched connectivity and home security devices with Amazon, Ring, and Comcast and captured design wins at Garmin supporting mobile fitness applications. In automotive, we supported autonomous driving systems with a market-leading Robotaxi platform and enabled advanced Charge Control Unit systems for a Tier 1 European automotive OEM.
Across the infrastructure markets, we provided power isolation solutions to a strategic manufacturer of EV including residential solar and energy storage systems, and we secured multiple design wins in next-generation MIMO and small cell base station installations. Moving ahead, we see a multiyear secular technology evolution with our aperture widening from smartphones to industrial, automotive, and an expansive set of IoT devices. Skyworks is fueling this dramatic technological shift with our unique capabilities, integrating not only 5G, but increasingly with our other critical connectivity protocols, including high-performance Wi-Fi, Bluetooth, and precision GPS. As these opportunities emerge, Skyworks is positioned to win.
With the breadth and depth of our customer relationships established over 20 years, our experience across multiple technology transitions, and a dedicated and talented workforce that executed extraordinarily well during fiscal 2021. With that, I will turn the call over to Kris.
Kris Sennesael -- Chief Financial Officer
Thanks, Liam. Skyworks revenue for the fourth fiscal quarter of 2021 was $1.311 billion, up 17% sequentially and up 37% year over year, driven by both mobile solutions and broad markets. Gross profit in the fourth quarter was $668 million, resulting in a gross margin of 51% up 40 basis points sequentially and 60 basis points year over year. Operating expenses were $180 million or 13.8% of revenue, demonstrating leverage in our operating model while continuing our strategic investments in support of future growth.
 We generated $488 million of operating income, translating into an operating margin of 37.2%. We incurred $11 million of other expenses, and our effective tax rate was 8%, driving net income of $439 million. So, top-line momentum and execution on margins drove diluted earnings per share of $2.62 ahead of consensus estimates. EPS grew 22% sequentially and increased 42% compared to Q4 of last year.
Turning to the balance sheet and cash flow. Fourth fiscal quarter cash flow from operations was $398 million. Capital expenditures were $263 million, and we paid $93 million in dividends and repaid $250 million of our term loan. Let's also review our record-breaking full fiscal year performance.
Revenue grew 52% to $5.1 billion, adding over $1.7 billion in incremental revenue over fiscal 2020. Gross profit was $2.6 billion, resulting in a gross margin of 50.9%. Operating income increased 73% to $2 billion with an all-time record operating margin of 38.2%, up 450 basis points from the prior year. Net income was $1.8 billion, translating into $10.50 of diluted earnings per share, up 71% year over year.
Cash flow from operations was up 47% to $1.8 billion. And during fiscal 2021, we returned $536 million of cash back to the shareholders with $340 million in dividends and $196 million in share buybacks, all during Q1 of fiscal '21. Starting in Q2 of fiscal '21, we temporarily suspended our share repurchase program in connection with the acquisition of the Infrastructure & Automotive business from Silicon Labs. Given the strength of our business and the progress we have made on integrating the acquisition and given the low leverage ratio 