The 29-year-old actress-writer confirmed the sad news that Lashaway had passed in a post on her Instagram account.
Alongside a photo of the two colleagues working on a scene together, she wrote, "Nick was such a talented, funny and kind person and we were so lucky to have him as part of the Girls family when he played Frank in episode 207," she added.
"We will always remember the week we shared with him, his playful smile and his easy instincts and how much he made us laugh when we had to stay up all night in the woods. We are sending love to his family and friends and feeling such gratitude for his gifts. RIP sweet Nick."
The 28-year-old actor was pronounced dead at the MetroWest Medical Center hours later.
Besides his role in "Girls", Lashaway also appeared in the movies "The 40-Year-Old Virgin", "In Time" and "The Last Song" opposite Miley Cyrus and Liam Hemsworth.
Richard Shepard, who directed Lashaway in the 2013 episode, has added his tribute, tweeting: "Sad news. Nick Lashaway who was so great in my GIRLS ep 'Video Games' has died at 28. Funny, sweet & talented. RIP.