The 22-year-old was born in Bristol but would have qualified for Wales later this month on the three-year residency rule.
After weighing up his options, Morgan has opted to make himself available for England and he will immediately come into consideration for Six Nations selection.
Morgan said: "I feel privileged and honoured that both Wales and England have been following me.
"It has taken me a while to think over and discuss with my family before I came to the decision of where I'd like to focus my ambitions for the future.
"But I'm English, I grew up supporting England and as a youngster I always dreamt of playing for England one day.
"Ultimately, if given the opportunity at international level, I want to try and take things forward with my home country."
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.