A series of solid supramolecules based on acrylamide–phenylpyridium copolymers with various substituent groups (P−R: R=−CN, −CO2Et, −Me, −CF3) and cucurbit7uril (CB7) are constructed to exhibit tunable second‐level (from 0.9 s to 2.2 s) room‐temperature phosphorescence (RTP) in the amorphous state. Compared with other solid supramolecules P−R/CB7 (R=−CN, −CO2Et, −Me), P−CF3/CB7 displays the longest lifetime (2.2 s), which is probably attributed to the fluorophilic interaction of cucurbiturils leading to a uncommon host–guest interaction between 4‐phenylpyridium with −CF3 and CB7. Furthermore, the RTP solid supramolecular assembly (donors) can further react with organic dyes Eosin Y or SR101 (acceptors) to form ternary supramolecular systems featuring ultralong phosphorescence energy transfer (PpET) and visible delayed fluorescence (yellow for EY at 568 nm and red for SR101 at 620 nm). Significantly, the ultralong multicolor PpET supramolecular assembly can be further applied in fields of anti‐counterfeiting and information encryption and painting. Solid supramolecules based on acrylamide–phenylpyridium copolymers with various substituent groups and cucurbit7uril not only exhibit tunable ultralong phosphorescence with lifetimes varying from 0.9 s to 2.2 s, but also co‐assemble with organic dyes Eosin Y or SR101 to display high‐performance phosphorescence energy transfer with multicolor delayed fluorescence properties.