The artist's contract with the publisher expired on Saturday, making his Ray miniseries his last exclusive project.
"Frankly, this has been a long time coming," Igle wrote on his blog.
"While I was very happy for many years to be exclusive, there comes a time when you're ready to move on. There's no animosity, in fact just the opposite.
"I've never been calmer or more centred than I have since I made this decision. I was forced to turn down a lot of outside opportunities while I was exclusive because I was so busy that I couldn't take them on or contractually unable to do them.
"So what does this mean? Well, for one I already have some comics work coming up, which will be announced soon, as well as securing other work in and out of the industry.
"I'm also available for work as well. I'll be taking private commissions and developing some projects and pitching some of the creator owned concepts I've been working on over the last few years."
Igle has been in an exclusive contract with DC for the past seven years.
He was recently announced as one of the guests at the London Super Comic Convention, which is being headlined by Stan Lee in February.
The Ray is written by Jimmy Palmiotti and Justin Gray. Issue #2 will go on sale on January 11.