What was Skyworks' gross profit in the first fiscal quarter of 2020 
ng. Our baseband agnostic solutions offer interoperability and are being deployed across leading chipset suppliers, including MediaTek, Samsung and Qualcomm. And with our expanding filter capabilities in TC SAW and bulk acoustic wave, we help our customers navigate complex challenges while extending our reach across a broader spectrum of 4 and 5G bands.
Moving onto broad markets, at CES, Skyworks announced a unique set of 5G-enabled solutions, including Massive MIMO IoT, a suite of connected home devices and high fidelity smart audio products. Specifically we are powering rapidly emerging IoT applications with cellular-based platforms certified by KDDI, NTT DoCoMo SoftBank and Verizon. We're driving growth with the launch of our Wi-Fi 6 platforms, expanding our customer reach with industry leaders including AT&T, Cisco, Netgear, ARRIS and Aruba.
We're advancing automotive content with SkyOne in our emerging V2X portfolio and supplying low power, long range IoT products as [Phonetic] Ring and many others.
In the infrastructure space Skyworks is leveraging its capabilities in silicon germanium SOI, gallium arsenide, bulk acoustic wave and ceramic filters while powering 5G MIMO and small cell base station design wins. In addition, we are gaining momentum in automotive, enabling new wins with leaders like Continental, Nissan and Renault along with industrial players including Honeywell, Bosch and GE.
As these highlights suggest, we remain focused on driving diversification across high value segments and markets with more than 2,000 products, supporting thousands of customers. So in summary Skyworks has decades of connectivity experience across multiple technology transitions. Uniquely positioning us to meet the performance demands of 5G are portfolio of highly integrated customized connectivity engines bolstered by the early strategic investments we have made anticipating both the complexity and the immense opportunity across our end markets and finally, a highly profitable and predictable business model that allows us to invest aggressively while providing consistent returns to our shareholders.
With that, I will turn the call over to Kris for a discussion of Q1 and our outlook for Q2.
Kris Sennesael -- Senior Vice President and Chief Financial Officer
Thanks, Liam. Skyworks' revenue for the first fiscal quarter of 2020 was $896 million, up 8% sequentially and $16 million above the midpoint of the outlook we provided in November, driven by the successful launch of flagship phones and the early success of our Sky5 product portfolio as new 5G phones start ramping globally.
Gross profit in the first quarter was $449 million resulting in a gross margin of 50.1% in line with expectations. Operating expenses were $134 million, down 4% year-over-year as we continued to prudently manage opex while making the necessary investments to accelerate future growth of the business. We generated $315 million of operating income, translating into an operating margin of 35.2%, up 120 basis points from fiscal Q4.
Other income was $1 million and our effective tax rate was 8.9%, driving net income of $289 million or $1.68 of diluted earnings per share up 11% sequentially.
Turning to the balance sheet and cash flow. First fiscal quarter cash flow from operations was $398 million, capital expenditures were $111 million, resulting in $287 million of free cash flow on $896 million of revenue translating into a strong free cash flow margin of 32%. We paid $75 million in dividends and repurchased 742,000 shares of our common stock for a total of $74 million. During the last 12 months, we have returned 87% of free cash flow back to the shareholders through a combination of our dividends and share buyback program. We ended the first fiscal quarter with cash and investments of $1.2 billion and we have no debt.
Now let's move on to our outlook for Q2 of fiscal 2020. Early momentum from the initial launch of 5G as we ramp design wins in our mobile business matched with solid traction in broad markets are driving better than seasonal performance in the Marc
ng. Our baseband agnostic solutions offer interoperability and are being deployed across leading chipset suppliers, including MediaTek, Samsung and Qualcomm. And with our expanding filter capabilities in TC SAW and bulk acoustic wave, we help our customers navigate complex challenges while extending our reach across a broader spectrum of 4 and 5G bands.
Moving onto broad markets, at CES, Skyworks announced a unique set of 5G-enabled solutions, including Massive MIMO IoT, a suite of connected home devices and high fidelity smart audio products. Specifically we are powering rapidly emerging IoT applications with cellular-based platforms certified by KDDI, NTT DoCoMo SoftBank and Verizon. We're driving growth with the launch of our Wi-Fi 6 platforms, expanding our customer reach with industry leaders including AT&T, Cisco, Netgear, ARRIS and Aruba.
We're advancing automotive content with SkyOne in our emerging V2X portfolio and supplying low power, long range IoT products as [Phonetic] Ring and many others.
In the infrastructure space Skyworks is leveraging its capabilities in silicon germanium SOI, gallium arsenide, bulk acoustic wave and ceramic filters while powering 5G MIMO and small cell base station design wins. In addition, we are gaining momentum in automotive, enabling new wins with leaders like Continental, Nissan and Renault along with industrial players including Honeywell, Bosch and GE.
As these highlights suggest, we remain focused on driving diversification across high value segments and markets with more than 2,000 products, supporting thousands of customers. So in summary Skyworks has decades of connectivity experience across multiple technology transitions. Uniquely positioning us to meet the performance demands of 5G are portfolio of highly integrated customized connectivity engines bolstered by the early strategic investments we have made anticipating both the complexity and the immense opportunity across our end markets and finally, a highly profitable and predictable business model that allows us to invest aggressively while providing consistent returns to our shareholders.
With that, I will turn the call over to Kris for a discussion of Q1 and our outlook for Q2.
Kris Sennesael -- Senior Vice President and Chief Financial Officer
Thanks, Liam. Skyworks' revenue for the first fiscal quarter of 2020 was $896 million, up 8% sequentially and $16 million above the midpoint of the outlook we provided in November, driven by the successful launch of flagship phones and the early success of our Sky5 product portfolio as new 5G phones start ramping globally.
 Gross profit in the first quarter was $449 million resulting in a gross margin of 50.1% in line with expectations. Operating expenses were $134 million, down 4% year-over-year as we continued to prudently manage opex while making the necessary investments to accelerate future growth of the business. We generated $315 million of operating income, translating into an operating margin of 35.2%, up 120 basis points from fiscal Q4.
Other income was $1 million and our effective tax rate was 8.9%, driving net income of $289 million or $1.68 of diluted earnings per share up 11% sequentially.
Turning to the balance sheet and cash flow. First fiscal quarter cash flow from operations was $398 million, capital expenditures were $111 million, resulting in $287 million of free cash flow on $896 million of revenue translating into a strong free cash flow margin of 32%. We paid $75 million in dividends and repurchased 742,000 shares of our common stock for a total of $74 million. During the last 12 months, we have returned 87% of free cash flow back to the shareholders through a combination of our dividends and share buyback program. We ended the first fiscal quarter with cash and investments of $1.2 billion and we have no debt.
Now let's move on to our outlook for Q2 of fiscal 2020. Early momentum from the initial launch of 5G as we ramp design wins in our mobile business matched with solid traction in broad markets are driving better than seasonal performance in the Marc