Valentine is the former president and chief executive officer of the United Paramount Network, a position he held from 1997 to 2001. He was responsible for the overall administration of UPN and its programming, distribution, affiliate relations, marketing, advertising, and advertising sales and research activities.

Under his tenure, Valentine transformed UPN into a true destination for young viewers seeking an alternative brand of programming. While overseeing the network’s expansion from three to five nights, Valentine radically improved it’s finances.

In April 2001, Valentine orchestrated a network-television coup by acquiring the sensational hit series "Buffy the Vampire Slayer." When the show debuted on UPN in October 2001, it delivered its best ratings ever. Valentine also developed the latest installment of the long-running Star Trek franchise, "Enterprise," which premiered in the fall of 2001 to 12.5 million viewers, UPN’s largest primetime audience since the network’s launch on January 16, 1995. He also brought the smash hit "WWF Smackdown!" to UPN and strengthened the network’s distribution base.

Before that, Valentine served as the President of Walt Disney Television and Walt Disney Television Animation. He was responsible for all creative and business areas, including the development and production of television series, specials and telefilms produced by Walt Disney Television, Walt Disney Television Animation and Touchstone Television for network, syndication, basic cable and pay-TV markets.

During his tenure at the studio, Valentine oversaw the creation and production of such top-rated shows as "Home Improvement" and the history-making "Ellen", as well as "Soul Man", "Boy Meets World" and "Smart Guy." He was also involved with long-running hits "The Golden Girls," "Blossom" and "Empty Nest."

Additionally, he oversaw the development and production of an ambitious slate of original telefilms and event movies for the revived "The Wonderful World of Disney," including "Rodgers and Hammerstein’s Cinderella," starring Whitney Houston and Brandy, "Oliver Twist," starring Richard Dreyfuss, and "Toothless," starring Kirstie Alley.

In animation, Valentine expanded the scope of Walt Disney Television Animation and led the resurgence of Disney’s Saturday morning animation lineup on ABC. He is responsible for signing noted industry writers and producers such as Peter Hastings, creator of "Pinky and the Brain," acquiring Jumbo Pictures, Inc. (producers of "Brand Spanking New Doug)", and signing production deals with innovative animation houses such as Colossal Pictures.

Valentine developed the "Disney’s One Saturday Morning" block for ABC which premiered as the #1 kid’s programming block in 1997. Shows he oversaw for ABC’s Saturday morning schedule included: "Brand Spanking New Doug," "Mighty Ducks," "Jungle Cubs" and animated series’, "Recess," "Pepper Ann," and "101 Dalmatians: The Animated Series."

Valentine was responsible for overseeing six series on the studio’s syndicated "The Disney Afternoon," including "Mighty Ducks," "Quack Pack," "The Lion King’s Timon & Pumbaa," "Gargoyles," "Disney’s Aladdin" and "Darkwing Duck."

Fall 1997 Marked the syndication premiere of "101 Dalmatians: The Animated Series" via the Disney/Kellogg alliance with episodes exclusive to syndication airing five days a week. "Mighty Ducks," "Quack Pack" and the classic children’s series "DuckTales" also aired in syndication during the 1997-98 season.

Valentine’s responsibilities also included developing the immensely successful Disney Video Premiere line of sequels to Disney’s animated theatrical features which were produced as direct-to-video properties. These projects included the first full-length "Winnie the Pooh" feature, "Pooh’s Grand Adventure: the Search for Christopher Robin," "Beauty and the Beast: The Enchanted Christmas," "The Lion King II: Simba’s Pride," "Pocahontas: Journey to a New World," "An Extremely Goofy Movie," "The Little Mermaid II: Return to the Sea," "Lady & the Tramp II: Scamp’s Adventure," and Hunchback of Notre Dame II." Valentine also oversaw the production of the Emmy Award winning "Boo! To You Too Winnie the Pooh" and the Emmy nominated "A Winnie the Pooh Thanksgiving" and "Winnie the Pooh, a Valentine For You." In addition, Valentine developed and greenlighted the theatrical animated movies "The Tigger Movie," "Return to Neverland," and "Doug’s First Movie."

Valentine began his career at Disney in 1988 as director of television development. In May 1989, he was promoted to vice president and then to senior vice president in April 1990. Before joining Disney, Valentine served as director of Current Comedy Programming at NBC Entertainment. Prior to that, he held a number of key positions at New York based magazines including Life and Saturday Review.

In 1995, Valentine was instrumental in establishing the industry’s first Director’s Training Program in association with the Director’s Guild of America, which aims to improve the industry’s employment record of talented minority directors. He was nominated by the DGA for the first annual Diversity Award which honors an employer or producer who has demonstrated consistent commitment to, and leadership in, the hiring of women and ethnic Minorities in DGA categories.

An honors graduate of the University of Chicago with a degree in English Language and Literature, Valentine is the founder of the Academy of Arts and Sciences’ Archive of American Television, a trustee of the Museum of Contemporary Art (MOCA), and a member of the KCRW Board, Los Angeles.