The colloquial adjective adorkable means: unfashionable or socially awkward in a way regarded as appealing or endearing.

This adjective is a blend of adorable and dork.

The noun dork denotes an odd, socially awkward, unstylish person.
—Cf. also origin of the word ‘geek’.

The noun dork is perhaps an alteration of dick. The following is from Some Problems in the Study of Campus Slang, by Lawrence Poston, III, of the University of Nebraska, published in American Speech (Durham, North Carolina: Duke University Press) of May 1964:

The word dick itself serves as a model for two variants which are probably Midwestern, dirk and dork, also meaning “penis;” on at least one Midwestern campus, a dirk may be an “oddball” student, while a prick (more common) is of course an offensive one.

These are, in chronological order, the earliest occurrences of the adjective adorkable that I have found:

1-: From Valentine Wishes, published in the Los Angeles Times (Los Angeles, California) of 14^th February 1999:

♥ TIM-MAN ♥
You Are The Love Of My Life!
ADORKABLE……DEB

2-: From an interview of Adam Brody (born 1979), who played Seth Cohen in The O.C., a U.S. teen drama television series, originally broadcast from 5^th August 2003 to 22^nd February 2007—interview published in Newsweek (New York City, New York) of 21^st September 2003:

Fast Chat: What It’s Like To Be The Adorkable One

[…]
Newsweek’s B. J. Sigesmund spoke with star Adam Brody about everyone’s new addiction.
[…]
Your character has been called “one of the most endearing nerds ever to stumble through a series.”
That feels great. Someone called me “adorkable.” Anyone who says they don’t care about reviews or feedback is either lying or an idiot.

3-: From the review of Win a Date With Tad Hamilton! (2004), a U.S. romantic comedy film starring Topher Grace (born 1978)—review by Carol Cling, published in the Las Vegas Review-Journal (Las Vegas, Nevada) of 23^rd January 2004:

It’s Grace who proves the movie’s most valuable player, deploying his sitcom-honed comedic chops—and the dramatic prowess he demonstrated in “Traffic” ¹—to create the kind of adorkable, aw-shucks hero who’s been getting the girl (and winning audience’s hearts) since Jimmy Stewart’s Hollywood prime.

¹ Traffic (2000) is a U.S. crime drama film directed by Steven Soderbergh (born 1963).

4-: From The Indiana Gazette (Indiana, Pennsylvania) of 25^th September 2004:

Reality O.C.

Television’s “The O.C” has become a pop-culture phenomenon, challenging “90210” ² on the teenage-intensity scale. This fall, however, TV viewers will get a look at the competition, the so-called “real Orange County.”
MTV is introducing “Laguna Beach,” a reality series that chronicles the lives of a group of teenagers in southern California’s affluent Orange County. Does everyone really live on the beach? Are the miniskirts really so mini? Do all residents enjoy fistfights on a regular basis? And, of course, will there be a heartthrob as “adorkable” as Seth Cohen?

² The first U.S. teen drama television series in the Beverly Hills, 90210 franchise was originally broadcast from 4^th October 1990 to 17^th May 2000.