TechCrunch founder Michael Arrington is resigning as editor of the popular technology blog, and will run a $20 million venture-capital fund backed by TechCrunch-owner AOL Inc. and several venture-capital firms.

Mr. Arrington "will run the fund and will continue to write for TechCrunch, but will have no editorial oversight," said an AOL spokesman. Erick Schonfeld, who has served as co-editor in New York, will become interim editor while AOL searches for a replacement for Mr. Arrington, the spokesman said. AOL purchased the site last year.

Mr. Arrington's new fund, called CrunchFund, closed Thursday with $20 million, according to people familiar with the matter. AOL leads the limited-partner group, which includes a long roster of venture firms that kicked in $1 million each: Accel Partners, Austin Ventures, Kleiner Perkins Caufield & Byers, Greylock Partners, Redpoint Ventures and Sequoia Capital.

Several individuals contributed money, including Marc Andreessen and Ben Horowitz of the venture firm Andreessen Horowitz; general partners at Benchmark Capital; angel investors Ron Conway and Kevin Rose; and Yuri Milner of Russian firm DST Global.

It isn't immediately clear what is the fate of AOL's venture-capital arm, AOL Ventures, which has made recent seed investments in start-ups such as spam-defense company Impermium and price-tracking service Shopobot.

Mr. Arrington's partner in the fund is Patrick Gallagher, who has been a partner at VantagePoint Capital Partners since 2008.

Mr. Arrington wasn't immediately available for comment. He posted a message on Twitter after news of the fund broke: "slow news day."

Mr. Arrington, a former lawyer who is known to be well connected in Silicon Valley, started TechCrunch in 2005. The site built up a following for its coverage of young tech companies.

Long an angel investor himself, Mr. Arrington announced on TechCrunch in 2009 that he would stop making investments in start-ups due to a perceived conflict as both publisher and investor. It's "a weak point that competitors and disgruntled entrepreneurs use to attack our credibility," he wrote at the time.

But in April this year, after AOL acquired TechCrunch, Mr. Arrington announced he was investing in start-ups again, while also becoming a limited partner in venture funds Benchmark Capital and SoftTechVC.

Mr. Arrington has often said that transparency and full disclosure keep things above-board when his blog writes about companies he has some financial stake in.

—Ty McMahan and Zoran Basich contributed to this article.

Write to Scott Austin at scott.austin@dowjones.com