His performances earned him a place in the MLS Best XI for 2018 and DC United's former England captain believes there is more to come next season.
Wayne Rooney said DC United's achievements exceeded his expectations as he predicted an "exciting time" ahead despite their play-off defeat to Columbus Crew.
The 33-year-old's transfer from Everton in June prompted a revival in United's fortunes, the club rising from the bottom of the Eastern Conference to finish fourth as Rooney scored 12 goals and made seven assists.
His performances earned him a place alongside Zlatan Ibrahimovic and Josef Martinez in the MLS Best XI for 2018 and Rooney reflected on his first five months in America with satisfaction.
"We went on a great run, making the play-offs and finishing fourth in the league," Rooney told MLS.
"At the time I joined I don't think we realistically expected to finish that high up. Obviously disappointed to go out on penalty kicks.
"We've set foundations now. We're looking to build on the momentum we've built up. We'll try and start the season well next season and try to kick on."
He continued: "From my first week training with the team I knew there was ability in the squad.
"Did I think we would go on the run we did? Probably not, but the team grew, as a team and as individuals, and showed great character to help us get there.
"The way we ended the season was an exciting time for the team and fans and it leads to an exciting time coming up.
"This has to be the marker we've put down to improve on. It's on us as players and on the club to move forward and that's what we'll be looking to try to do.
"It's early to put down expectations and we don't know what's going to happen with players coming in and players going out.
"Once we know what our squad is we can start to set goals for the season, but we need to move forward and our first goal has to be to make the play-offs."
Disappointing result last night but there’s a lot of positives to build on for next year. Just want to thank all the fans and everybody at @dcunited for your support and making me and my family feel so welcome. Looking forward to next season already👍🏼👏🏼⚫️🔴 #DCU pic.twitter.com/EfJ8p9z8b6— Wayne Rooney (@WayneRooney) 2 November 2018
2018 MLS Best XI
Goalkeeper: Zack Steffen (Columbus Crew)
Defenders: Kemar Lawrence (New York Red Bulls), Aaron Long (New York Red Bulls), Chad Marshall (Seattle Sounders).
Midfielders: Luciano Acosta (DC United), Miguel Almiron (Atlanta United), Ignacio Piatti (Montreal Impact), Carlos Vela (Los Angeles FC).
Forwards: Zlatan Ibrahimovic (LA Galaxy), Josef Martinez (Atlanta United), Wayne Rooney (DC United).