Waghorn spent the 2017/18 season at Ipswich, scoring 16 goals in 39 starts after signing from Rangers for £250,000.
He later moved to Derby for an initial £5M, rising to £7.5M, shortly after Paul Hurst took charge.
“It’s been an incredible journey,” Waghorn wrote on social media.
“I’ve been very fortunate to play for some great clubs in my career and never took that for granted, Charlton, Leicester, Hull City, Millwall, Wigan, Rangers, Ipswich, Derby, Coventry, Huddersfield and Northampton. I am proud to have worn the shirt of every one of these great clubs.
“Every time I stepped on the pitch all I wanted to do was make my family proud. There has been some amazing memories with friends and family that I will cherish forever.
“Thank you to everyone at Sunderland for giving me the opportunity in the game. You believed in me from seven years old until my debut at 17, thank you all.
“To represent my country at various age groups was always an honour and to also score on my England U21 debut was such a proud moment.
“Thank you to everyone who has been there and supported me along the way. I would like to mention some great academy coaches Elliot Dickman, Ged McNamee and Kevin Ball to name a few, but also everyone who helped me during my time at the academy. The friends and people I’ve met along the way… it’s been some journey.
“My family, thank you. Honestly, I don’t know where I would be with you all. Mam and Dad thank you for all the sacrifices you made for me and with me, starting at Boldon Colts with you Dad, what an amazing journey we’ve been on.
“Leoni, Ruben and Enzo, I can’t put into words how grateful I am to have had you by my side in my career. To share amazing memories and moments with you is something I will cherish forever.
“I’m looking forward to the next chapter of my life and career as a dad and a husband. Thank you, Waggy.”